Search PubMed⌕ Search

Biomedical subjects

F Bayard

Publications and source records attributed to F Bayard.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

The mitogenic effect of 17beta-estradiol on in vitro endothelial cell proliferation and on in vivo reendothelialization are both dependent on vascular endothelial growth factor.

In addition to their actions on reproductive function, estrogens have important effects on endothelial cells. The present study was designed to evaluate the mechanism(s) by which 17beta-estradiol (E2) promotes endothelial cell proliferation. The potential involvement of vascular endothelial growth factor (VEGF) was investigated by the coadministration of polyclonal anti-VEGF antibody. First, the effect of E2 on the proliferation of cultured foetal bovine aortic endothelial cells (FBAEC) was studied. E2 stimulated this proliferation with an EC50 between 10(-11) and 10(-10) M and this effect was inhibited by the anti-VEGF antibody. The effect of a physiological dose of E2 was then studied in the rat model of carotid injury. After deendothelializing balloon injury, reendothelialization of the denuded surface may influence the growth of the underlying smooth muscle cells. Male Sprague-Dawley rats were castrated and then received E2 from subcutaneously implanted pellets that released 3.2 microg/kg/day. Endothelial regrowth (Evans blue staining) and neointimal thickening were evaluated 2 weeks after the carotid injury. In comparison to the placebo group, E2 increased the extent of reendothelialization (p = 0.0002) and reduced neointimal thickening (p = 0.0007). Anti-VEGF antibody abolished the effect of E2 on reendothelialization as well as on neointimal thickening. Thoracic aorta VEGF content was increased in E2-treated rats compared to control rats. In conclusion, the present study demonstrates that E2 increases endothelial cell proliferation in vitro and reendothelialization in vivo by means of a mechanism dependent on endogenous VEGF. This effect could contribute to the antiatherogenic effect of a physiological dose of E2.

Animals↗
PubMedDate not supplied

[Effect of estrogens on arterial physiology and mechanisms of their atherosclerosis-protective effect in animals].

Two isoforms of oestrogen receptors (alpha and beta) have been identified in the cells of the arterial wall, and a heterogeneity of their expression according to the animal species, the vascular beds and the sex has been reported. Oestrogens can thus directly influence the vascular physiology through a 'genomic' mechanisms, but 'extra-genomic' mechanisms responsible for a short-term effect have also been suggested. Oestrogens potentiate endothelium-dependent relaxation through an increase in nitric oxide bioavailability (increase in its production and/or decrease in its degradation by superoxide anion according to the vascular beds). Endothelial 'dysfunction' (abnormality of the endothelium-dependent vasodilation) occurs in atheromatous arteries. Oestrogen replacement prevents and even corrects this endothelial dysfunction. In monkeys, this beneficial effect of oestrogens is not altered by coadministration of progesterone, but is abolished by coadministration of medroxyprogesterone. Finally, oestrogens prevent fatty streak deposit, and the mechanisms of this atheroprotective effect are being studied.

Animals↗
PubMedDate not supplied

[Determination of prolactin].

Prolactin is a pituitary stimulating hormone which is capable of inducing and maintaining lactation. The recent introduction of very sensitive methods of estimating the levels have led to its isolation and identification of its physico-chemical characteristics in the human and also to the physio-pathological study of its secretion. The authors demonstrate a human homologous radio-immune level estimating technique which uses a human anti-prolactin serum obtained from the rabbit human prolactin highly purified with iodine 125 using the lacto-peroxydase method. This radio-immune level estimation constitutes a feasible and satisfactory approach for the base level of prolactin. The spread of results which have been obtained, however, showed that one sole estimation is not sufficient. The authors draw attention to the need to carry out dynamic tests of stimulation or of braking in order to reveal possible abnormalities of prolactin secretion.

Animals↗
PubMedDate not supplied

[Plasma concentrations and urinary excretion of gonadotropins in azoo and oligospermia. Relationship with spermatogenesis and plasma concentration of androgens (author's transl)].

Plasma concentrations and urinary excretions rate of gonadotropins, testosterone, delta 4-androstenedione, dehydroepiandrosterone and 17 and 17 alpha-hydroxyprogesterone plasma concentrations have been studied in 69 patients with oligo or azoospermia and compared with results obtained in 30 normal control subjects. A sperm count and a caryotype have been done in all patients and a testicular biopsy in 35. Analysis of the histo-hormonal correlations does not show a particular stage of spermatogenesis associated with a modification in FSH production. There is a quantitative relationship between spermatogenesis and FSH production. Plasma testosterone is low and LH production normal in excretory azoospermia. In the other patients plasma testosterone is also low but associated with an increased production of LH. Finally there is a direct relationship between urinary excretion of LH and FSH in both normal subjects and patients, suggesting a modulation by specific factors of a common regulation of the secretion of both gonadotropins.

Adult↗
PubMedDate not supplied

[Variations in the estradiol and progesterone receptors in human endometrium during the menstrual cycle].

The concentration of estradiol and progesterone "receptors", both cytoplasmic and nuclear, has been measured in human endometrium during the menstrual cycle using an exchange assay method. A rapid increase of the concentration of the two "receptors" has been observed during the proliferative phase followed by a striking decrease during the secretory phase. New physiological and pharmacological aspects may be derived from these results.

Endometrium↗
PubMedDate not supplied

[Bone and calcium metabolism in adult hypothyroidism (author's transl)].

A study of blood and urinary calcium and phosphorus, 25 hydroxyvitamin D plasma level (25 OH D3), bone radiology and hystology is performed in 12 hypothyroïd adult patients. This study confirms the notion of myxoedematous ostéopetrosis. Radiologic and histologic findings shows an osteocondensation, more important on the skull, and augmentation of cortical thickness of the bones is noted. Quantitative histologic findings, shows some signs of diminution of bone cellular activity. Low plasma level of 25 OH D3 in these patients is discussed in the view of an event of a disturb in the metabolism of D-vitamin in hypothyroïdism.

Adult↗
PubMedDate not supplied

[Estrogen dependance of the progesterone "receptor" in human tissues (author's transl)].

The concentration of specific progesterone receptor (RP) has been measured in the endometrium of 31 normal menstruating women during the two phases of their menstrual cycle, and compared with the plasma oestradiol-17 beta (E2) concentrations. There was no relationship between RP and plasma E2 when the two phases of the cycle were considered, however a correlation was observed when the follicular phase was only considered. The relationship between oestrogen and RP was then more directly studied in a breast cancer cell line in tissue culture (MCF-7). RP induction by E2 as well as oestriol was demonstrated, but oestrone was ineffective.

Endometrium↗
PubMedDate not supplied

[Comparative effects of tamoxifen and estorgens on the induction of progesterone receptors and uterine growth in rats].

Effects of prolonged administration (7 days) of Tamoxifen (Tx: 100 micrograms/day), oestradiol-17 beta (E2; 1 microgram/day) and oestriol (E3; silastic capsules) on the uterine weight, protein, DNA and progesterone receptor (RP) content of prepubertal rats have been studied. It has been observed when compared with E2 that Tx induces a dissociated action after two days of administration; the RP content is still increasing when the other parameters are at a constant level. E3 has a similar action to E2.

Animals↗
PubMedDate not supplied

[A computerised study of 124 cases of varicocoele which were operated on for diminished fertility. General features (author's transl)].

A computerised study has been carried out on the general features of a clinical, biological and histological nature occurring in 124 varicocoele cases that were operated. These features were furthermore studied in correlation with the degree of varicocoele in existence and whether characteristics were found in isolation or in association with one another. The authors conclude that there were significant correlations between the degree of varicocoele present and the hormonal and histological findings. They advance a theory about the transport of testosterone in the spermatic cord which can explain the low level of testosterone found in the blood in these varicocoeles.

Adult↗