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Biomedical subjects

A Guichard

Publications and source records attributed to A Guichard.

At least 19 recordsLinked to original sources
PubMed1996

Alternative splicing of the Drosophila melanogaster rotundRacGAP gene.

The rotund (rn) gene in Drosophila melanogaster codes for a RacGTPase-activating protein, RnRacGAP. Cellular studies have shown that RacGAP proteins function as negative regulators of substrate Rac proteins which, in turn, control the localization and polymerization state of actin within the cell. Previous sequence analysis of rn genomic DNA and incomplete cDNA clones suggested that at least two differentially spliced forms of the transcript exist, rnRacGAP(1) and rnRacGAP(2). Using nested reverse transcription-polymerase chain reaction (RT-PCR) methods, we have cloned missing exon and intron sequences, and detected differences between rnRacGAP(1) and rnRacGAP(2) involving 24 nucleotides (nt) of coding sequences and 119 nt of 3'UTR. This translates to a difference of seven amino acids at the C-termini of the polypeptide products. Utilization, in RT-PCR analysis, of form-specific primers provided a simple assay for the tissue specificity of expression of the two forms. rnRacGAP(1) is the predominant species in the testes and is expressed at a low level in the ovary and somatic tissues. rnRacGAP(2) is only very weakly expressed and is detectable solely in the testes.

Alternative Splicing↗
PubMed1991

Predictive value of the active renin assay for the diagnosis of ectopic pregnancy.

The increasing frequency of EP and the need for its early diagnosis have focused our interest on the research of biochemical markers. We have established hormonal values in the plasma of 99 spontaneous ongoing pregnancies between the 4th and 10th weeks of amenorrhea, in 21 EPs, and 20 cases of early abortion. We have examined the predictive values of trophoblastic and CL production in pathological pregnancies. The association of low hCG and low active renin appears to be able to discriminate between ectopic and abortive spontaneous gestations.

Abortion, Spontaneous↗
PubMed1990

Retrograde tubal transfer of human embryos.

This preliminary study was designed to evaluate retrograde cannulation of the Fallopian tubes up to the isthmo-interstitial junction using the new technique of tubal embryo stage transfer (TEST). Follicular aspiration was performed under the guidance of a vaginal ultrasound probe in 51 women treated with GnRH + HMG. The oocytes retrieved were inseminated in vitro with 50,000 motile spermatozoa and kept in Menezo B2 medium without serum, at 37 degrees C, in an atmosphere of air + 5% CO2. The eggs were checked 24 and 36 h after insemination. No fertilization occurred in 23 patients. Cleaved embryos were obtained in the 28 other patients. One to seven embryos at the 2-4-cell stage were transferred with the 'Baudelocque Black Catheter' (BBC) into one tube and spare embryos were frozen. Five pregnancies occurred after retrograde TEST, for a pregnancy rate of 9.8% per cycle and 17.9% per transfer. One patient has given birth to a normal full-term baby. One singleton and one twin pregnancy are ongoing (8 months in June 1989). The other two pregnancies were ectopic.

Adult↗
PubMed1989

Lack of correlation of immunosuppressive activity secreted by human in vitro fertilized (IVF) ova with successful pregnancy.

The high rate of implantation failure in humans following in vitro fertilization (IVF) has been attributed to a lack of production of immunosuppressive factors by cleaved embryos, rendering them vulnerable to maternal immune attack just before or around implantation. Systemic as well as blastocyst-secreted suppressor factors have been described and claimed to be responsible for successful pregnancy. Experimentally, we have screened in a double-blind fashion the suppressive activity of human embryo culture media (B2 Menezo system, France) in which zygotes after decoronization were individually cultured during 24 hr on lymphocyte proliferation as well as natural killer (NK) activity. Suppressive activity in media from cleaved and uncleaved ova did not differ significantly, and activity in media from transferred embryos was not correlated significantly with successful pregnancy. The implications of these data are discussed.

Analysis of Variance↗
PubMed1989

Immunoreactive renin variations during fertile and infertile hyperstimulated cycles with in-vitro fertilization and embryo transfer or gamete intra-fallopian transfer.

The concentrations of prorenin (PR) and active renin (AR) were determined sequentially during ovarian hyperstimulated cycles for in-vitro fertilization-embryo transfer or gamete intra-Fallopian transfer. AR and PR increased during the early luteal phase and PR was highly correlated with the progesterone concentration. In fertile cycles, AR increased more rapidly after HCG injection and AR and PR levels were significantly higher during the late luteal phase. These results confirm the role of the renin angiotensin system in ovarian physiology.

Adult↗
PubMed1989

Salivary oestradiol in spontaneous and stimulated menstrual cycles.

The determination of steroids in saliva provides useful information in the clinical study of various endocrine functions, and salivary progesterone concentration has been widely used for assessing corpus luteum function during the spontaneous menstrual cycle and early pregnancy. However, the determination of oestradiol in saliva (SE2) has previously been found unsatisfactory. SE2 profiles and saliva/plasma E2 ratios were established (during the different periods of the menstrual cycle) by a highly sensitive radioimmunoassay method during normal menstrual cycle. During cycles hyperstimulated for in-vitro fertilization and embryo transfer, the SE2 pattern is similar to the corresponding profile in plasma with a peri-ovulatory oestradiol peak. There is a significant difference between fertile and non-fertile cycles with a higher saliva/plasma ratio in conception cycles.

Adult↗
PubMed1988

Ovarian programming and GIFT.

The procedures used for programming and ovarian stimulation in GIFT are identical to those used for in-vitro fertilization. At the Baudelocque Hospital, the hypophyseal gonadal axis is suppressed by administering a gonadotrophin-releasing hormone analogue (Decapeptyl, D-Trp-6-LHRH). Programming for the week of GIFT is then possible by controlling three stages: the beginning of treatment, which is independent of the date of the patient's period, the duration of treatment, which has 5 days' maximum variation, and an end-point of suppressing the spontaneous LH surge.

Female↗
PubMed1988

[Immunoradiometric assay for active renin and plasma prorenin during cycles stimulated by IVFET or GIFT].

Prorenin (PR) an inactive high molecular weight form of renin normally circulates in human plasma at a concentration of about 10 times that of active renin (AR) and this proenzyme seems to be linked to the reproductive function. It has been demonstrated that AR and PR are present at high concentrations in follicular fluid when the ovaries are stimulated with gonadotropins and that the PR plasma levels increase steadily after hCG injection with a correlation between blood PR and the number of developing follicles and corpora lutea. From September 1986 we studied the profile of immunoreactive active renin (AR) and prorenin (PR) in plasma during hyperstimulated cycles for IVFET or GIFT. All women were treated with a protocol combining GnRH analog (Decaptyl Ipsen Biotech, Paris France) and human menopausal gonadotropins until injection of 5,000 IU hCG. AR has been assayed in frozen samples by specific immunoradiometry (Renin RIA code 79 795, Pasteur Diagnostic, France) using two complementary monoclonal antibodies. A second assay of total renin was carried out after trypsin activation which revealed the inactive form. Progesterone (P), estradiol (E2) were measured by radioimmuno-assays. During the follicular phase, from day 1 of hMG administration to the day before hCG, no significant difference could be found between two groups, 63 pregnant or 60 nonpregnant cycles matched for age and number of oocytes retrieved, for E2, P, PR and AR. During the periovulatory period (D - 1, Do = day of hCG injection and D 1) no difference could be found for E2, P and PR (tabl. 1). In the 2 groups the mean E2 levels increased after hCG injection, as well as P and PR. But a significant difference appeared for AR which increased in the plasma immediately after hCG administration in the pregnant group whereas it decreased in the non-pregnant group (+2.5 vs -2 pg/ml) the mean variation between Do and D + 1 being significantly different in fertile cycles and in nonfertile cycles.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1987

Progesterone and estradiol in saliva after in vitro fertilization and embryo transfer.

The importance of the luteal function to ensure adequate implantation prompted us to assay salivary estradiol (SE2) and salivary progesterone (SP) concentration serially after embryo transfer by simple and rapid radioimmunoassays to allow a noninvasive easily repeatable approach. SE2, which has fallen 1 day after human chorionic gonadotropin injection, increased after reimplantation (day 3), plateaued during approximately 1 week, and returned to basal levels before menstruation in absence of conception or in chemical pregnancy, whereas it increased steadily in successful pregnancy. SP increased in all the cases, formed a plateau, and returned progressively to basal levels before menstruation, whereas in ongoing pregnancy there was a transitory decline in the midluteal phase followed by a rapid and continuous increase, with a significantly higher ratio day 13/day 10 in successful pregnancy.

Adult↗
PubMed1986

Inhibin concentration in the culture media of human oocyte-cumulus-corona cell complexes is not related to subsequent embryo cleavage.

We have demonstrated an in vitro secretion of inhibin by human OCCC, not related to subsequent egg cleavage. A putative signal, released by OCCC, that could modulate inhibin secretion by granulosa cells has not been discovered. Inhibin secretion by OCCC has no predictive value concerning the further fertilization and cleavage of the oocytes.

Blastomeres↗
PubMed1985

Early sex differences in hormonal potentialities of gonads from quail embryos with a sex-linked pigmentation marker: an in vitro radioimmunoassay study.

Quail embryos with a sex-linked eye pigmentation marker allowing sex identification at autopsy provided a biological model for radioimmunoassay of sex steroids in embryonic quail gonads at a very early stage (51/2 and 61/2 days). The purpose was to demonstrate a sex difference in hormonal potentialities of the gonads before any morphological indication of sexual differentiation. Evidence of early steroidogenesis by undifferentiated gonads could be obtained: estrogen synthesis characterized female gonads, while testosterone was produced by the gonads of both sexes. The sex hormonal production was concomitant with, or even preceded, the apparent beginning of sex differentiation of gonads.

Animals↗
PubMed1984

Effects of early tamoxifen treatment on hormonal content of 15-day quail embryo gonads.

An early treatment of quail eggs with an antiestrogen (Tamoxifen = TAM) modifies the female gonads morphologically. In the left ovary, the proliferation of the germinal epithelium and formation of a cortex is markedly inhibited, while the medulla on both sides becomes more developed and keeps a cordal organization. The effects of TAM on the hormonal potentialities of 15-day embryo gonads have been investigated by radioimmunoassay. The data have been compared with those of normal gonads. The results indicate that the TAM treatment does not mainly modify the hormonal levels and patterns in the gonads of both sexes and does not inhibit the function of the hypothalamo-hypophyseal-gonadal axis. The reduced cortical development is thus not linked to an estrogen decrease but to competitive effects on receptors at the level of this tissue.

Animals↗
PubMed1983

Control of the hormonal secretions of quail embryo gonads (normal and DES-treated): in vitro effects of testosterone and of hCG.

In vitro effects of factors such as testosterone or hCG on steroidogenesis by 12-day quail embryo gonads have been investigated by radioimmunoassays. The purpose was to compare the hormonal potentialities (estradiol, estrone, and dihydrotestosterone; E1, E2, DHT) of normal and diethylstilbestrol-treated gonads. The results demonstrate that the reduced steroid production by the treated ovaries does not result from their inability to respond to both factors, but reflects their weakened stimulation in vivo at the time of explantation. On the other hand, the secreting abilities of the DES-treated male gonads do not greatly differ from those of normal testes; even in the presence of favorable factors, and despite their feminization, the ovotestes are effectively unable to produce significative amounts of estradiol. These results are compared with others obtained elsewhere in quail and in chick embryos.

Animals↗
PubMed1983

[Attempt at determining fetal sex by the simultaneous study of the HY antigen and testosterone in the amniotic fluid].

Attempts have been made to determine fetal sex early by a simultaneous study of H-Y antigen and testosterone in amniotic fluid. H-Y (male) antigen was serologically detected in the amniotic cells from both sexes, but the results obtained from 473 amniotic fluids showed no significant sex differences either in fresh cells or after culture. Testosterone assays done from 263 samples of liquor confirm that the results obtained in cases of male fetuses were significantly higher than in females. 55% of all males and 47% of females could thus be detected to a level of 100% certainty. The probability of having a girl decreases as an inverse function of testosterone levels and comes out at 85% for testosterone less than 200 pg/ml. On the other hand the probability of a male fetus is 95% when the values are above 240 pg/ml. The determination of the testosterone/DHA ratio in order to try to eliminate the influence of the variations in volume has not improved the accuracy of this diagnosis.

Adult↗