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Biomedical subjects

Marc Dhont

Publications and source records attributed to Marc Dhont.

14 recordsLinked to original sources
PubMed2003

Poor response after hormonal stimulation for in vitro fertilization is not related to ovarian aging.

OBJECTIVE: To investigate whether the diminished efficacy of ART in young poor responders compared to young normal responders is due to a quantitative or a qualitative oocyte factor. DESIGN: Retrospective comparative analysis. SETTING: University-based infertility center. PATIENT(S): Nine thousand six hundred forty-four patients who underwent ART procedures at our hospital from 1993 until 2001. INTERVENTION(S): Controlled ovarian hyperstimulation, ultrasonographic monitoring of the ovarian response, oocyte retrieval, ART procedure, embryo transfer, and follow-up of pregnant patients until 12 weeks of amenorrhea. MAIN OUTCOME MEASURES: Clinical rates of pregnancy and miscarriage. RESULT(S): Nine thousand six hundred forty-four ART cycles were analyzed. The pregnancy rate for poor responders was significantly lower than for normal responders (17% vs. 35%). In cycles in which two good-quality embryos were transferred, the pregnancy rate was similar in poor responders and normal responders (33% vs. 42%). The rate of miscarriage was no higher in poor responders than normal responders. CONCLUSION(S): Young poor responders have a lower pregnancy rate than young normal responders because they have fewer oocytes, which leads to fewer good-quality embryos to choose from for transfer. The quality of their oocytes and embryos is not inferior to that of normal responders.

Abortion, Spontaneous↗
PubMed2003

Creation of a neovagina with use of a pudendal thigh fasciocutaneous flap and restoration of uterovaginal continuity.

OBJECTIVE: To create a neovagina and an endocervival canal in two patients with vaginal aplasia and a functioning uterus. DESIGN: Technique and instrumentations. SETTING: University hospital. PATIENT(S): A 31-year-old woman with vaginal aplasia and a double noncommunicating uterus (classified as Mayer-Rokitansky-Kuster-Hauser syndrome) and a 19-year-old woman with partial vaginal aplasia and a functional uterus. INTERVENTION(S): Creation of a neovagina by using the bilateral pudendal thigh fasciocutaneous flap procedure and laparotomy to establish uterovaginal continuity. MAIN OUTCOME MEASURE(S): Clinical follow-up evaluation of restoration of outflow of menstrual blood and coital satisfaction. RESULT(S): Uterovaginal continuity was established in both patients, resulting in normal menstruation. Granulomatous polyps occurred in one patient, and stenosis at the site of anastomosis occurred in the other patient; these conditions were successfully managed. Unimpeded menstrual flow continued after 1 year of follow-up in one patient and 3 years of follow-up in the other patient. CONCLUSION(S): Bilateral fasciocutaneous pudendal thigh flaps permit vaginal reconstruction and a uterovaginal connection in patients with vaginal agenesis and a functional uterus. The main advantages of this technique are that postoperative dilatation is not necessary, sensation is maintained, and the resulting scar is inconspicuous. The main disadvantage is the presence of some sebaceous vaginal secretion and hair in the vaginal lining; the latter can be managed by preoperative and postoperative laser depilation.

Adult↗
PubMed2003

Enzymatic differentiation of Candida parapsilosis from other Candida spp. in a membrane filtration test.

A previously reported enzyme assay on a membrane filter using 4-methylumbelliferyl (4-MU)-N-acetyl-beta-D-galactosaminide, -phosphate and -pyrophosphate as substrates for the differentiation of four Candida spp. has been extended to Candida parapsilosis. The substrate 4-MU-beta-D-glucoside was hydrolyzed by 28 test strains of this species but to a variable extent by seven other yeasts also. For a full enzymatic differentiation of C. parapsilosis from other medical yeasts, a battery of six reactions was required. Of 71 C. parapsilosis positive clinical samples, 4.2% gave a false negative result due to overgrowth by Candida albicans. The present assay is more rapid than a described spectrofluorometric determination of beta-D-glucosidase in a broth, i.e., 9-11 h versus up to >48 h.

Acid Phosphatase↗
PubMed2003

Risk of spontaneous abortion in singleton and twin pregnancies after IVF/ICSI.

BACKGROUND: The risk of spontaneous first trimester abortion is estimated to be between 10 and 20%. Although it is common knowledge that the incidence of abortion decreases as pregnancy progresses, exact data in relation to the duration of pregnancy are scarce. METHODS: We reviewed 1597 clinical IVF/ICSI pregnancies with known outcome and tabulated the number of miscarriages or fetal demise per intervals of 2 weeks. We furthermore compared the outcome in terms of fetal survival of 1200 singleton pregnancies with that of 397 twin pregnancies. RESULTS: The overall incidence of non-ongoing singleton pregnancies was 21.7%. Fetal death, after positive heart activity had been recorded, occurred in 12.2% of singleton pregnancies. The overall incidence of spontaneous abortion in twin pregnancies was 17.1% (12.1% vanishing twins and 5.0% complete miscarriages). The incidence of miscarriage in the twin pregnancies, expressed per gestational sac, was 11.1%. Once fetal heart activity was present, the risk of abortion (per gestational sac) was 7.3%, which is significantly lower than that in singleton pregnancies. CONCLUSIONS: Our data give an estimate of the probability of miscarriage or fetal demise at any given period of the first trimester both for singleton and twin pregnancies. Twin pregnancies after IVF have a better potential for survival than singleton pregnancies.

Abortion, Spontaneous↗
PubMed2003

In vitro parthenogenetic development of mouse oocytes following reciprocal transfer of the chromosome spindle between in vivo-matured oocytes and in vitro-matured oocytes.

Mouse follicles grown in vitro from preantral to mature stages yield oocytes that can be fertilized in vitro, but embryonic development is poor. To investigate whether this poor development is due to a nuclear or a cytoplasmatic factor, we designed an experiment in which the MII chromosome spindle was exchanged between in vitro-matured oocytes and in vivo-matured oocytes by electrofusion. Subsequent embryo development was evaluated by blastocyst formation rate and blastocyst cell number after parthenogenetic activation. Electrofusion was successful in 62-78% of the oocytes. Transfer of the spindle apparatus from in vitro-matured oocytes to the in vivo MII cytoplasmic environment resulted in a high rate of blastocyst development, whereas in the reverse situation (transfer of the nucleus from in vivo-matured oocytes into in vitro-matured MII cytoplasm) poor quality embryos and a low rate of blastocyst formation was observed. These results indicate that the low developmental competence of in vitro-matured oocytes from mouse preantral follicles after activation is caused by the cytoplasmic component rather than the nuclear component.

Animals↗
PubMed2003

Recurrent miscarriage.

Recurrent miscarriage is defined as the occurrence of three consecutive pregnancy losses during the first trimester. Although it affects only 1% of all couples, it is a most frustrating experience for the patient as well as for the clinician. Frustrating for the couple because they rarely obtain clear-cut reasons for the repeated failure to sustain a pregnancy, nor the prospect of a fail-safe treatment; frustrating for the clinician, too, because it is extremely difficult to disentangle the causes of sporadic and unavoidable miscarriage--most of which have a genetic background--from those of recurrent miscarriage. In the latter case, an underlying defect can potentially be detected and, ideally, should be amenable to treatment. Unfortunately, however, this is rather exceptional. In this paper, literature on genetic, anatomic, endocrine, metabolic, and autoimmune aspects of recurrent miscarriage are reviewed, and a survey of meaningful investigations and treatment is provided.

Abortion, Habitual↗
PubMed2002

A health-economic decision-analytic model comparing double with single embryo transfer in IVF/ICSI.

BACKGROUND: Single embryo transfer (SET) is the sole strategy with which to reduce the incidence of twins following assisted reproductive technology (ART), but SET may increase the number of ART cycles needed per live-born child. Its cost-effectiveness compared with double embryo transfer (DET) is therefore unknown. METHODS: A decision-analytic model comparing SET with DET was developed. Estimates were obtained from literature, national pregnancy registers and local hospital records. A sensitivity analysis was performed, using pregnancy rates from four published studies. The outcome measure was the cost per child born, calculated from IVF procedure-related, pregnancy-related and neonatal care costs. Neonatal mortality and long-term morbidity costs were not taken into account. RESULTS: Independently of the pregnancy rates used, the SET cost per child born was in all instances the same as with DET, varying from EURO= 9520 (SET) versus EURO= 9511 (DET) to EURO= 12254 (SET) versus EURO= 12934 (DET). CONCLUSIONS: More ART cycles are required to obtain the same numbers of children born following SET compared with DET. Because SET allows the avoidance of twins and thus diminishes pregnancy-related and neonatal care costs, there is no difference in the cost per child born between SET and DET. The real advantage of SET is the avoidance of the very high long-term costs resulting from the increased morbidity of twins after birth.

Cost-Benefit Analysis↗
PubMed2002

Early massive follicle loss and apoptosis in heterotopically grafted newborn mouse ovaries.

BACKGROUND: Ovarian tissue cryopreservation and transplantation can be used to restore fertility to sterile females. A question that warrants further investigation is whether the follicular content is affected by the freeze-thawing and grafting procedure, and if so, to what extent and by what mechanism. METHODS AND RESULTS: Intact newborn mouse ovaries were allografted under the kidney capsule or were cryopreserved by slow freezing with dimethylsulphoxide as the cryoprotectant prior to grafting. Estrogenic activity of ovariectomized recipient mice, as revealed by vaginal cytology, resumed after 11 days of transplantation. At 14 days after transplantation, ovarian grafts were recovered and processed histologically for follicle number counting. The follicular content of grafts of fresh ovaries was 58% of that from ovaries of age-matched 14 day old mice. In frozen-thawed ovarian grafts, the follicular content was only 9% lower than that of fresh grafted ovaries. Apoptosis of follicular cells was investigated by DNA nick end labelling. We observed a marked increase in the staining of fragmentation of DNA shortly after transplantation (2-12 h) of fresh newborn mouse ovaries. CONCLUSIONS: The results of the present study indicate that transplantation rather than cryopreservation accounts for the major and early loss of primordial follicles in grafted newborn mouse ovaries.

Animals↗
PubMed2002

Serial pronuclear transfer increases the developmental potential of in vitro-matured oocytes in mouse cloning.

In vitro-matured germinal vesicle oocytes are an interesting source of cytoplast recipients in both animal and human nuclear transfer (NT) experiments. We investigated two technical aspects that might improve the developmental potential of nuclear transfer mouse embryos constructed from in vitro-matured germinal vesicle oocytes. In a first step, the effect of two maturation media on the embryonic development of NT embryos originating from in vitro-matured oocytes was compared. Supplementation of the oocyte maturation medium with serum and gonadotrophins improved the developmental rate of NT embryos constructed from in vitro-matured oocytes, but it was still inferior to that obtained with in vivo-matured metaphase II (MII) oocytes. Second, we investigated the effect of serial pronuclear transfer from NT zygotes originating from both in vitro- and in vivo-matured oocytes to in vivo-fertilized zygotic cytoplasts. Blastocyst quality was evaluated by counting nuclei from trophectoderm and inner cell mass cells using a differential staining. Sequential pronuclear transfer significantly improved the blastocyst formation rate of NT embryos originating from in vitro-matured oocytes up to the rate obtained with in vivo-matured MII oocytes. We conclude that the developmental potential of NT embryos constructed from in vitro-matured oocytes can be optimized by serial pronuclear transfer to in vivo-produced zygotic cytoplasts.

Animals↗
PubMed2002

Fertilization of mouse oocytes from in vitro-matured preantral follicles using classical in vitro fertilization or intracytoplasmic sperm injection.

Early preantral mouse follicles with a diameter of 110-160 microm were cultured in vitro for 10 or 12 days. Mature oocytes were retrieved following hCG, and fertilization was attempted either by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Two-cell and blastocyst formation rates and blastocyst cell numbers were compared between 10-day and 12-day in vitro-matured oocytes versus in vivo-matured oocytes. Uncleaved IVF oocytes were subjected to chromosome analysis. The 2-cell formation rate was significantly improved by ICSI compared with IVF both in 10-day (72.1% versus 56.1%; P = 0.03) and 12-day cultures (74.1% versus 54.5%; P = 0.028). Cytogenetic analysis of uncleaved MII oocytes following IVF showed that about 30% of MII oocytes showed no sign of sperm penetration. The blastocyst formation rate was significantly lower in 12-day versus 10-day cultures, whether fertilization was by IVF (40.7% versus 62.4%, P = 0.016) or by ICSI (32.5% versus 57.1%, P = 0.035). Blastocyst cell numbers from IVF and ICSI 10-day groups were similar and both significantly higher (P < 0.001) than from IVF 12-day cultures. All above expressed values were significantly higher for in vivo-matured oocytes. In conclusion, fertilization of oocytes from in vitro-matured mouse preantral follicles can be optimized with ICSI, giving significantly higher 2-cell formation rates than IVF. Blastocyst formation rate was not influenced by the technique of fertilization but rather by the extent of the in vitro culture period. Best results on preimplantation development of oocytes for in vitro-matured preantral follicles were obtained with ICSI on oocytes from 10-day in vitro cultures.

Animals↗
PubMed2001

Ovarian tissue cryopreservation: therapeutic prospects and ethical reflections.

Along with improved survival, methods to preserve or restore the fertility potential of young women and children treated with cytotoxic chemotherapy or pelvic radiotherapy have been developed or are in the offing. Surgery, radiotherapy and chemotherapy can all impact on the future ovarian function, but patient and disease tailored application and use of preventive measures can limit ovarian damage. When the loss of reproductive ovarian function is unavoidable, different alternatives to preserve fertility or at least to restore the procreative potential are available. Creation of embryos by IVF, oocyte donation and cryopreservation of mature or immature oocytes are potential issues, the advantages and limitations of which are discussed. Recently, ovarian tissue cryopreservation has spurred interest in the medical literature as well as in the lay press as a method for preservation and restoring fertility. Considering the available data and current state of knowledge, we want to stress that this methodology is still in an experimental phase and we would like to caution against unwarranted enthusiasm of physicians and patients. The medical information preceding the informed consent should mention the actual uncertainties of this method. Moreover, the imperative character of the offer and in particular for paediatric oncological patients, the force of the moral rules that define parental obligations towards children should not be ignored.

Journal Article↗
PubMedDate not supplied

Timing of FSH-stimulation and follicular development in cryopreserved human ovarian grafts.

Cryopreserved human primordial follicles grafted into immunodeficient hosts are susceptible to gonadotrophic stimulation but the optimal interval between grafting and stimulation has not been determined. The effect of stimulation with FSH at different time intervals after grafting was therefore investigated. Cryopreserved human ovarian cortical grafts from an androgen pre-treated female-to-male transsexual patient were transplanted into four groups of four non-obese, diabetic severe combined immune deficiency (NOD-SCID) mice. Ten, 12, 14 and 17 weeks after grafting, stimulation was started with daily intra-peritoneal injections of 5 IU of recombinant FSH for 14 days. Grafts were recovered and serially sectioned for counting the number of follicles and determining the different stages of development. Significantly more primary and secondary follicles were found in all stimulated groups compared with the non-stimulated control. This progression from the primordial to growing primary and secondary stages was most significant in the 14 weeks interval group. Formation of antral follicles was scarce and was only noticed in the 10 and 17 week groups. Cystic follicles and follicles with structural oocyte abnormalities were encountered in each group. Whether this phenomenon is related to the hormonal state of the tissue donor or to the cryopreservation and transplantation procedures is the subject of further investigation. It is concluded that the interval between grafting of ovarian tissue and the start of gonadotrophic stimulation may be important for an optimal follicular development after grafting.

Animals↗