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Biomedical subjects

N Chabbert-Buffet

Publications and source records attributed to N Chabbert-Buffet.

9 recordsLinked to original sources
PubMed2004

Measurement of the cutaneous blood flow reserve in normal humans by laser-Doppler flowmetry.

AIM: To assess the normality of the cutaneous blood flow reserve (CR). METHODS: To explore the feasibility and reproducibility of laser-Doppler flowmetry for CR measurement, we prospectively measured CR in 17 healthy subjects on the dorsum of the foot and pulp of the big toe. CR was defined as the sum of the venoarteriolar reflex (VAR), i.e. postural vasoconstriction, and postischemic reactive vasodilation (H), expressed as % of the resting supine flux and assessed by using laser-Doppler flowmetry. RESULTS: For the dorsal foot, VAR%+/-SEM was 61+/-14, H%, 752.5+/-214 and CR, 813.5+/-217. On the pulp of the big toe, VAR% was 61.6+/-4.7, H%, 588.2+/-174 and CR, 649.9+/-176. CR measurement variability was assessed by calculating the inter-individual coefficient of variation of CR, which was 1.1 for both the dorsal foot and pulp of the big toe. Reproducibility was assessed by calculating the CR intraclass correlation coefficient, which was 0.49 for the dorsal foot and 0.64 for the pulp of the big toe. CONCLUSIONS: The CR is proposed as a new parameter for assessing the microvascular integrity and contractile reserve of the skin. Laser-Doppler flowmetry is suitable for this non-invasive evaluation. The method displayed large variability, and its reproducibility varied from moderate for the dorsal foot, to substantial for the toe. Further studies are necessary to demonstrate its clinical usefulness.

Blood Flow Velocity↗
PubMed2003

[Insulin resistance and polycystic ovary syndrome].

Polycystic ovary syndrome (PCOS) is a frequent disease, characterized by disturbed ovarian function with hyperandrogenism. Anovulation is secondary to an absence of follicular dominance. Apart from a primary ovarian defect, insulin resistance is observed in PCOS women, even in the absence of overweight. This insulin resistance could be secondary to a defect in the insulin transduction pathway, mainly by a defect in receptor phosphorylation. It enhances hyperandrogenism as it increases ovarian androgen production. Therefore treating insulin resistance by weight loss or drugs reducing insulin resistance might improve fertility of PCOS women. Metformin has been shown to reduce ovarian production, enhance ovulatory cycles and in some cases increase fertility. However, there are few randomized studies on large numbers of patients to prove an effect on pregnancies as well as on the occurrence of early pregnancy loss. There are currently no recommendation on dose and duration of metformin treatment. It is noteworthy that metformin has no authorization in France to be prescribed apart from diabetic patients' care. Considering the medical care of PCOS women, the cardiovascular risk needs to be taken into account. Therefore hypertension, dyslipidemia and diabetes must be treated in those women who need to be followed carefully all over their life.

Female↗
PubMed2003

Cutaneous microvascular effects of mid-term hormone replacement therapy in healthy postmenopausal women: a prospective placebo controlled trial.

OBJECTIVE: To study the mid-term effects of Hormone Replacement Therapy (HRT) on cutaneous microcirculatory blood flow and reactivity in healthy postmenopausal women. DESIGN: In a double-blind placebo controlled randomized study, 16 healthy postmenopausal women received either placebo or HRT (micronized estradiol: 1 mg/day, day 1-28, promegestrone: 0.25 mg/day, day 14-28). This regimen was completed 6 times. Cutaneous microcirculatory blood flow was recorded by laser-Doppler velocimetry on the foot dorsum, in the supine and then dependent positions, and after post-ischemic hyperemia. RESULTS: At day 0, the two groups were similar and none of the following data differed significantly between treated and placebo group: (supine flux: 11.8 +/- 1.8 u vs. 13.2 +/- 3.9, venoarteriolar reflex: 5.6 +/- 1.3 vs. 6 +/- 3.3, and post-ischemic hyperemia: 35.2 +/- 3.9 vs.48.3+/-11). At the end of the study (day 26-28 of 6th cycle), the supine flux was 9.8 +/- 2.1 in the HRT group vs.12.9 +/- 6 in the placebo group (NS), the venoarteriolar reflex, 1.2 +/- 2 vs. 7+/-1.7 (p=0.04), and post ischemic hyperemia, 31.8 +/- 5.4 vs. 39.5 +/- 4.6 (NS). Intragroup values did not change significantly for any of the microcirculatory parameters measured, which remained stable throughout the 6 months of the study. Intergroup values for these parameters did not change either, except for the venoarteriolar reflex, which was lower at the end of the study in the HRT (EP period, cycle 6 day 26-28) than placebo group (p=0.04). CONCLUSIONS: HRT does not impair the resting supine cutaneous microcirculation blood flow or post-ischemic hyperemia.

Double-Blind Method↗
PubMed2000

Effect of gonadotrophin-releasing hormone (GnRH) antagonist during the LH surge in normal women and during controlled ovarian hyperstimulation.

OBJECTIVE: Several studies have suggested that GnRH is instrumental in triggering the LH surge. The present studies were performed to evaluate the effect of GnRH antagonist administration in women after the beginning of the LH surge. DESIGN: In study one, six normal cycling women were given a GnRH antagonist (20 mg Nal Glu s.c.) during an unstimulated cycle. Nal-Glu was administered when the LH level was higher than 10 U/l and associated with an oestradiol (E2) level higher than 730 pmol/l. In study two, a GnRH antagonist (3 mg Cetrorelix, ASTA-Medica, Frankfurt, Germany) was administered on day 8 of an IVF-ET cycle, in 157 women. Eighteen women among this cohort received the antagonist, when their LH level was higher than 10 U/l. RESULTS: In normal volunteers (study one), Nal-Glu was administered on day 13.7 +/- 1.4 (mean +/- SD) of the cycle when the LH level was 13.7 +/- 3.5 U/l with an E2 plasma level reaching 980 +/- 131 pmol/l. Twenty-four hours after administration of the antagonist, the LH surge had been interrupted in all subjects; it was postponed in three of the women, and abolished in the remaining three. LH levels fell by 68.5%, E2 by 42% and FSH by 53.2%. In study two, LH plasma levels 24 h after the antagonist administration fell by 94%. No premature ovulation occurred in any of the patients treated. Administering the antagonist before (n = 139) or during the LH surge (n = 18) made no statistically significant difference to the results of the IVF-ET attempt. CONCLUSIONS: Our results indicate that GnRH is required throughout the gonadotrophin surge in women, not only for the initiation but also for the maintenance of the LH surge. In addition, in our study, the suppression of the rise in LH, when the antagonist was given during the surge, had no detrimental impact on IVF-ET outcome. This suggests, if confirmed on a larger scale, that late follicular phase GnRH antagonist administration to prevent the LH surge in controlled ovarian hyperstimulation (COH) is a safe and useful treatment.

Adult↗
PubMed1999

[Physiology and exploration of the gonadotropic axis].

The physiology of the hypothalamus-pituitary-gonadal axis includes endocrine interactions between the hypothalamopituitary system and the gonads, as well as paracrine interactions within the various endocrine glands of the reproductive system (pituitary, ovary, testis). The pulsatile secretion of GnRH by the hypothalamus stimulates the pulsatile secretion of gonadotropins (LH and FSH) by the pituitary. LH and FSH regulate the hormonal production of the gonads as well as gametogenesis. The steroid (oestradiol, progesterone, testosterone) and peptide (inhibins) hormones produced by the gonads regulate in turn hypothalamopituitary secretions. The exploration of the hypothalamo-pituitary-gonadal axis relies mainly on the analysis of few, carefully scheduled, basal state hormonal evaluations. A confrontation of these hormonal assessments with physical examination is crucial.

Follicle Stimulating Hormone↗
PubMed1999

Main inhibitor of follicle stimulating hormone in the luteal-follicular transition: inhibin A, oestradiol, or inhibin B?

The roles of oestradiol, inhibin A and inhibin B in the luteal-follicular transition were assessed by means of specific assays. Six premenopausal women were studied during a control and then a cycle treated with percutaneous oestradiol 0.1 mg/day from day 10 after the luteinizing hormone (LH) surge until day 4 of the following cycle. Inhibin A concentrations decreased similarly in control and treated cycles from day -5 to day 2, then increased in control cycle to 23.3 +/- 3.4 pg/ml on day 10 (mean +/- SEM). They remained low until day 5 in treated cycles and were lower than controls on day 10 (P < 0.01). Follicle stimulating hormone (FSH) concentrations increased on day 1 in controls and on day 5 in treated cycles when oestradiol concentration fell abruptly. Inhibin B concentrations remained low until day 1 in controls and day 4 in treated cycles. In both, inhibin B concentrations increased 1 day after FSH, peaking at 160 pg/ml. FSH concentrations began to plateau when inhibin B concentrations were >100 pg/ml and oestradiol concentrations below 200 pmol/l. These data suggest that inhibin A is not responsible for FSH suppression in the luteal phase and that the negative control of FSH shifts from oestradiol in the luteal phase to inhibin B in the mid-follicular phase.

Adult↗
PubMed1995

[Perspectives of contraception].

According to demographic provision, the world population will soon reach 6 billions. It is therefore urgent to increase women's access to well tolerated, efficient, low cost contraceptives. The primary goal is to inform women on their reproductive health and on the use of contraceptives. Secondly, new molecules should be shortly available: low dose estroprogestins containing new non androgenic progestins and 17 beta-estradiol, RU 486 as a post-coïtal pill, levonorgestrel or desogestrel containing IUDs. The daily intake of low dose antiprogestins to interfere with endometrial maturation is also currently studied. In the future, anti-FSH molecules or tissue-specific steroids could be designed.

Contraception↗