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Biomedical subjects

M Dhont

Publications and source records attributed to M Dhont.

At least 55 records · Page 3Linked to original sources
PubMed2000

Cryopreservation of human germinal vesicle stage and in vitro matured M II oocytes: influence of cryopreservation media on the survival, fertilization, and early cleavage divisions.

OBJECTIVE: To study the influence of low-sodium cryopreservation media (CPM) on the survival and development of frozen-thawed germinal vesicle (GV) stage and in vitro matured human oocytes. DESIGN: Prospective experimental study. SETTING: Academic hospital-based fertility center. PATIENT(S): Experimental groups: Oocytes cryopreserved at the GV (group A, n = 63 and group B, n = 64) or M II stage (group C, n = 62) with use of conventional (group A) or low-sodium CPM (groups B and C). Control groups: Sibling GV stage oocytes subjected to in vitro maturation (IVM; control group A, n = 64; control group B, n = 64). INTERVENTION(S): IVM, intracytoplasmic sperm injection and subsequent culture. MAIN OUTCOME MEASURE(S): Rates of survival, maturation, fertilization, and cleavage. RESULT(S): The postthaw survival was significantly lower in groups A (57.1%) and B (48.4%) compared to C (84.4%). In group A, maturation and cleavage rates were significantly lower, and fertilization rate was similar to controls (GVBD: 72.2% vs. 90.6%; progression to M II: 33.3% vs. 76.6%; cleavage: 42.9% vs. 88.2%; and fertilization: 58.3% vs. 69.4% in group A vs. control group A, respectively). There was no such difference in group B. In group C, despite a slight but significant lowering of the rate of 2 PN and an increase in that of 3 PN (2 PN: 47.4% vs. 70.2% and 3 PN: 15.8% vs. 3.2% in group C vs. total controls, respectively), embryonic cleavage per GV oocyte was significantly higher (25.8%) compared to group A (4.8%) but not to group B (15.6%). The rate of maturation and cleavage per surviving GV oocyte was significantly higher in group B than group A. CONCLUSION(S): Low-sodium-based CPM is beneficial for in vitro matured M II stage oocytes and is significantly better than the conventional sodium-based media for the GV stage oocytes.

Cell Survival↗
PubMed2000

Fertilization, pregnancy and embryo implantation rates after ICSI in cases of obstructive and non-obstructive azoospermia.

The aetiology of azoospermia can be grossly divided into obstructive and non-obstructive causes. Although in both cases testicular spermatozoa can be used to treat male fertility, it is not well established whether success rates following intracytoplasmic sperm injection (ICSI) are comparable. Therefore, a retrospective analysis of fertilization, pregnancy and embryo implantation rates was performed following ICSI with testicular spermatozoa in obstructive or non-obstructive azoospermia. In total, 193 ICSI cycles were carried out with freshly retrieved testicular spermatozoa; in 139 cases of obstructive and 54 cases of non-obstructive azoospermia. The fertilization rate after ICSI with testicular spermatozoa in non-obstructive azoospermia was significantly lower than in obstructive azoospermia (67.8% versus 74.5%; P = 0.0167). Within the non-obstructive group, the fertilization rate in the group of maturation arrest (47.0%) was significantly lower than in case of Sertoli cell-only (SCO) syndrome (71.2%) or germ cell hypoplasia (79. 5%). Embryo quality on day 2 after ICSI was similar for all groups. Pregnancy rates per transfer between obstructive (36.8%) and non-obstructive groups (36.7%) were similar. In cases of maturation arrest the pregnancy rate per transfer was lowest (20.0%) although not significantly different from SCO syndrome or hypoplasia groups. Embryo implantation rates were not different between the obstructive (19.6%) and non-obstructive groups (25.8%), and were lowest in cases of germ cell hypoplasia (15.8%). This retrospective analysis shows that although fertilization rate after ICSI with testicular spermatozoa in non-obstructive azoospermia is significantly lower than in obstructive azoospermia, pregnancy and embryo implantation rates are similar.

Adult↗
PubMed2000

Maturation of mouse primordial follicles by combination of grafting and in vitro culture.

Cryopreservation of ovarian cortical tissue and subsequent transplantation or in vitro culture of follicles are technologies under development with the aim to safeguard fertility in patients with gonadal failure. In the present study, we investigated whether primordial follicles could be triggered to full maturation by a combination of in vivo transplantation and in vitro culture in a mouse model. In a first step, newborn mouse ovaries containing only primordial follicles were allotransplanted under the renal capsule of ovariectomized recipient mice. The second step was to mechanically isolate growing preantral follicles from the graft and culture these in vitro to maturity. In our experiment, one newborn mouse ovary was transplanted under the renal capsule of each 8- to 12-wk-old F1 (C57Bl/6j x CBA/Ca) female ovariectomized recipient (n = 26). Two weeks after transplantation, all 26 grafts were recovered. Four grafts were processed for histology and showed that developmental stages of follicles in 14-day-old ovarian grafts were comparable to those in 14-day-old mouse ovaries. The 22 remaining grafts were used for mechanical isolation of preantral follicles. As a control group, preantral follicles isolated from ovaries of 14-day-old mice were used. The mean preantral follicle yield per ovary was 11 in the transplant group versus 33 in the control group. Follicles were cultured individually in 20-microliter droplets of alpha-MEM supplemented with 100 mIU rFSH and 5% fetal bovine serum for 12 days under an atmosphere of 5% CO(2) in air at 37 degrees C. By Day 12 of culture, 66.5% of follicles retained their oocytes in the grafting group versus 97.5% in the control group (P < 0.001). Final oocyte maturation was induced by addition of 2.5 IU/ml hCG. At 14-16 h post-HCG, the percentages of oocytes showing germinal vesicle breakdown and polar body extrusion were significantly higher in the control group (90.6% and 82.8%) compared to the grafting group (60% and 45%). The mean diameter of the mature oocytes of the grafting group (69.9 +/- 4.45 micrometer) was similar to that of oocytes from the control group (70.5 +/- 2.35 micrometer). Our results suggest that maturation of mouse primordial follicles is feasible by combination of in vivo transplantation and in vitro culture. This two-step strategy may be an attractive model for promoting the growth and maturation of primordial follicles from other species.

Animals↗
PubMed2000

A comparison of cycle control and effect on well-being of monophasic gestodene-, triphasic gestodene- and monophasic desogestrel-containing oral contraceptives. Gestodene Study Group.

This was an open-label multicenter study to compare the cycle control and effect on well-being of two oral contraceptives containing gestodene and one containing desogestrel. A total of 2419 healthy women < or = 41 years of age were randomized to receive oral contraceptives containing monophasic gestodene (Minulet; n = 806, mean age 24.5 years), triphasic gestodene (Tri-Minulet; n = 808, mean age 24.6 years) or monophasic desogestrel (Mercilon; n = 805, mean age 24.6 years). Subjects were to participate in the study for up to 13 treatment cycles. A modified Moos Menstrual Distress Questionnaire was used to evaluate menstrual symptoms and to assess overall well-being. A total of 698 women were withdrawn from the study, 154 due to adverse events. Cycle control with gestodene was superior to that with desogestrel at almost all time points, particularly for breakthrough bleeding and/or spotting, which occurred significantly less frequently with gestodene than with desogestrel at cycles 1-7 and 9-11 (p < 0.05). Generally, the proportion of subjects with breakthrough bleeding and/or spotting was almost twice as great with desogestrel as with gestodene. The duration of bleeding was not consistently different between the gestodene and desogestrel groups; however, the intensity of bleeding was greater with gestodene at all time points (p < 0.05). The latent period before withdrawal bleeding was significantly longer for monophasic gestodene at cycles 1-5 and 8-10 (p < 0.05). Treatment significantly improved overall well-being at cycles 6 and 9 with triphasic gestodene and at cycle 13 with desogestrel; however, no statistically significant differences among treatment groups in overall well-being scores or individual factors of well-being could be identified. All three treatments were well tolerated. The most common drug-related adverse events were headache (14.2%), breast pain (6.2%), nausea (4.1%), metrorrhagia (3.9%) and abdominal pain (3.5%). The incidence of adverse events in all treatment groups was similar, with the exception of metrorrhagia, which occurred in more patients in the desogestrel group than in the gestodene treatment groups (p < 0.05).

Adolescent↗
PubMed1999

Perinatal outcome of pregnancies after assisted reproduction: a case-control study.

OBJECTIVE: We conducted a case-control study of all pregnancies obtained with assisted reproduction technology in the Dutch-speaking part of Belgium from 1992 until 1997 to investigate differences in peripartum obstetric events and the perinatal outcome. STUDY DESIGN: Three thousand fifty-seven singleton and 1241 twin pregnancies were studied. About 90% of pregnancies resulted from in vitro fertilization; the remainder resulted from intracytoplasmic sperm injection. Control subjects were selected from a regional register and were matched for maternal age, parity, fetal sex, plurality, and date of delivery. The main outcome measures were duration of gestation, birth weight, perinatal death, perinatal morbidity, incidence of congenital malformations, and incidence of cesarean delivery. RESULTS: Odds ratios and 95% confidence intervals were 2.6 (1.4-4.8) for perinatal mortality, 3.5 (2.2-5.7) for birth before 33 weeks of gestation, and 1.7 (1.5-1.9) for cesarean delivery in singleton pregnancies that resulted after in vitro fertilization. Twin pregnancies obtained with in vitro fertilization, on the contrary, were similar for all outcome measures, except for the incidence of cesarean delivery (odds ratio, 1.4; 95% confidence interval, 1.2-1.7) compared with spontaneously conceived twin pregnancies. CONCLUSION: The perinatal outcome of singleton pregnancies obtained with in vitro fertilization is significantly worse than that of spontaneously conceived pregnancies, mainly because of the increased rate of preterm birth. The outcome of twin pregnancies obtained with in vitro fertilization is comparable with that of normally conceived twins. For both singleton and twin pregnancies obtained with in vitro fertilization, the incidence of cesarean delivery is increased.

Adult↗
PubMed1999

Fertilization abnormalities and pronucleus size asynchrony after intracytoplasmic sperm injection are related to oocyte postmaturity.

OBJECTIVE: To study the effect of delayed intracytoplasmic sperm injection (ICSI) on the fertilization and cleavage of human in vitro matured (IVM) oocytes. DESIGN: Prospective experimental study. SETTING: Academic hospital-based fertility center. PATIENT(S): The experimental group consisted of 73 spare germinal vesicle-stage oocytes from 25 patients. The control group consisted of sibling in vivo matured oocytes from the same patients that were subjected to ICSI in the clinical program. INTERVENTION(S): Equal numbers of sibling IVM oocytes were subjected to ICSI either soon after maturation (30 hours, group 1) or after a 6-hour delay (36 hours, group 2). In a subsequent set of experiments, spermatozoa were labeled with a fluorescent mitochondria-specific vital dye and injected into 17 IVM oocytes that were intentionally aged by 6-8 hours. The resultant zygotes were fixed. MAIN OUTCOME MEASURE(S): Incidence of fertilization and cleavage, numbers and mean diameters of pronuclei, and incidence of zygotes with significant pronucleus size asynchrony. Identification of the male pronucleus by its proximity to the fluorescent sperm midpiece remnant. RESULT(S): Group 2 had significantly lower rates of normal fertilization (60%) than the control group (82.9%) and significantly lower cleavage rates (46.7%) than both group 1 (85%) and the control group (98.1%). The incidence of oocytes that developed one pronucleus and pronucleus size asynchrony was significantly higher in group 2 (32% and 40%, respectively) than in group 1 (4% and 5%, respectively) and in the control group (4.1% and 4.4%, respectively). All the zygotes with significant pronucleus size asynchrony that developed after delayed ICSI with labeled spermatozoa showed proximity of the fluorescent sperm midpiece remnant to the smaller pronucleus. CONCLUSION(S): For IVM oocytes, the incidence of one pronucleus, pronucleus size asynchrony (possibly related to a smaller male pronucleus), and cleavage failure increase when ICSI is delayed after maturation. Thus, the timing of ICSI is critical for optimum fertilization of IVM oocytes.

Cell Nucleus↗
PubMed1999

Prognostic factors in patients continuing in vitro fertilization or intracytoplasmic sperm injection treatment and dropouts.

OBJECTIVE: To investigate whether cumulative pregnancy rates using life table analysis but without considering dropouts are representative of the whole population of patients entering an in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) program. DESIGN: Retrospective study. SETTING: University hospital-based infertility center. PATIENT(S): One thousand one hundred sixty-nine patients entering our IVF/ICSI program from January 1993 to December 1996. INTERVENTION(S): Comparison of prognostic factors between pregnant and nonpregnant patients, and between patients continuing IVF/ICSI treatment and dropouts. MAIN OUTCOME MEASURE(S): Prognostic factors, such as patient age, cancellation of oocyte retrieval because of poor response to ovarian stimulation, number of oocytes retrieved, fertilization rate, number and quality of embryos transferred. RESULT(S): No statistical differences in prognostic factors were found between patients continuing IVF/ICSI treatment and dropouts. CONCLUSION(S): Cumulative pregnancy rates using life table analysis can be considered representative of the whole population of patients for at least the first three treatment cycles.

Adult↗
PubMed1999

Effect of post-ovulatory age and calcium in the injection medium on the male pronucleus formation and metaphase entry following injection of human spermatozoa into golden hamster oocytes.

The occurrence of parthenogenetic activation is a major hurdle in obtaining sperm chromosome metaphases after heterospecific intracytoplasmic sperm injection (ICSI) of golden hamster oocytes with human spermatozoa. We addressed two potential contributors to parthenogenetic activation namely, post-ovulatory age of the oocyte and Ca2+ content of the injection medium. In serial experiments, hamster oocytes were retrieved at 11.5, 13, 16 and 21 h after the ovulatory dose of human chorionic gonadotrophin (HCG) and microinjected with human spermatozoa suspended alternately in a regular (1.9 mM Ca2+) or a Ca2+-free medium. A progressive decrease in the rates of male pronucleus (MPN) formation and metaphase entry and increase in the rates of parthenogenetic activation without male pronucleus occurred with increasing post-ovulatory age. The favourable influence of Ca2+-free injection medium on the mean rates of MPN and metaphase entry was restricted to the relatively older oocytes (MPN 16 h: 49.5 versus 32.3%, P< 0.008; 21 h: 22.2 versus 11.1%, P< 0.001; metaphase entry 16 h: 36.8 versus 25.1%, P< 0.02; 21 h: 13.3 versus 5.2%, P< 0.01 in the Ca2+-free and regular groups respectively). Our data confirm the increased activation sensitivity with post-ovulatory ageing and its adverse influence on the MPN formation and metaphase entry after heterospecific ICSI of hamster oocytes.

Animals↗
PubMed1999

Presence and dynamic redistribution of type I inositol 1,4,5-trisphosphate receptors in human oocytes and embryos during in-vitro maturation, fertilization and early cleavage divisions.

We studied the presence and distribution of the intracellular calcium channel regulating type I inositol 1,4,5-trisphosphate receptors (IP3R) in human immature and mature oocytes, pronuclear zygotes and cleaved embryos using a specific antibody. Two approaches were used: (i) fluorescence immunocytochemistry using a confocal laser scanning microscope (CLSM) and (ii) Western blotting. With confocal microscopy, the receptors were found in the oocytes, fertilized zygotes as well as cleaved embryos at all stages studied. The pattern and distribution of the receptor staining in the oocytes changed gradually from a diffuse granular patchy one at the germinal vesicle (GV) stage to a reticular and predominantly peripheral one through the metaphase I and metaphase II (MII) stages. After fertilization, the distribution changed gradually to both, peripheral and central in the zygotes and early 2-4-cell embryos and predominantly perinuclear in the 6-8-cell embryos. Furthermore, an overall increase in the staining intensity was observed from GV to MII stage oocytes and from zygotes to 6-8-cell embryos. We also studied the spatial distribution of the receptor in detail by constructing three-dimensional images from the serial optical sections obtained on the CLSM. Peculiar peripheral aggregates of receptor clusters were noted in the MII stage oocytes, zygotes and some blastomeres from early cleaved embryos. Finally, Western blots performed on the extracts of 72 in-vitro matured oocytes and 50 spare cleavage stage embryos showed positive bands at approximately 260 kDa. These findings coincide with and thus possibly represent the dynamic changes occurring in the cellular Ca2+ release systems through oocyte maturation, fertilization and early embryogenesis. Thus, type I IP3R are likely to play a role during these stages of early development in the human.

Animals↗
PubMed1999

GyneFix-LNG: preliminary clinical experience with a copper and levonorgestrel-releasing intrauterine system.

A novel intrauterine contraceptive drug delivery system derived from the conventional GyneFix intrauterine implant system is described and the preliminary results in 22 women are discussed. The first objective of the development of the GyneFix-levonorgestrel system was to reduce menstrual bleeding, whether or not related to the effect of copper, by combining a shortened version of the standard GyneFix implant, having a copper surface area of 200 mm2, with a system for the sustained intrauterine delivery of levonorgestrel. The results of this initial observational study indicate that the GyneFix-levonorgestrel system, apart from being well tolerated, is safe and effective. The levonorgestrel component appears to have a beneficial effect on the amount of bleeding. A study on menstrual blood loss will be carried out to substantiate this assumption.

Adolescent↗
PubMed1999

GyneFIX. The frameless intrauterine contraceptive implant--an update for interval, emergency and postabortal contraception.

This article reviews the clinical experience with the GyneFix intrauterine implant system for interval, emergency and post-abortal contraception. The relatively high rate of unintended pregnancies and abortions in the world signifies that greater access to contraception is necessary. Unwanted pregnancies and abortions could be avoided by widening the range of effective and acceptable contraceptive methods for use in situations where current methods are far from optimal. High effectiveness, protection against sexual transmitted infections, long duration of action, reversibility and safety are some of the most important attributes of contraceptives valued by women. The development of the frameless intrauterine device is a response to the need to develop contraceptives with high user continuation rate. GyneFix has the lowest failure rate of all copper IUDs currently available. Its performance is further optimised by the atraumatic frameless design which minimises the side effects and discomfort experienced with conventional IUDs. GyneFix could, therefore, be a useful new contraceptive option in looking at ways to reduce the number of unwanted pregnacies and induced abortions.

Abortion, Induced↗
PubMed1998

Management of transient ovarian failure: pregnancy after in vitro fertilization and intracytoplasmic sperm injection--a case report.

PURPOSE: The case history of a 36-year-old patient with transient ovarian failure, presumably induced by previous ovarian surgery and a recent pelvic inflammatory disease, is described. METHODS: During several months, the patient underwent transvaginal ultrasound and hormonal follow-up. Ovulation was triggered by hCG in a cycle in which spontaneous follicular ripening had occurred. Transvaginal puncture of the single follicle was performed for in vitro fertilization. RESULTS: One oocyte was retrieved and fertilized by intracytoplasmic sperm injection, giving rise to a single good-quality embryo. A singleton pregnancy, which ended in the birth of a healthy daughter, was established. CONCLUSIONS: This case demonstrates that it is worthwhile to monitor patients with transient ovarian failure closely, and if other infertility factors are present, IVF of one oocyte may be considered.

Adult↗
PubMed1998

Prevention of severe ovarian hyperstimulation by coasting.

OBJECTIVE: To evaluate the efficiency of withholding gonadotropins and deferring the administration of hCG until E2 levels start dropping (coasting) in the prevention of ovarian hyperstimulation syndrome (OHSS) in a high-risk population. DESIGN: Retrospective case-control study. SETTING: In vitro fertilization program at a university center. PATIENT(S): The case group consisted of 120 women undergoing ovarian stimulation for IVF who were considered to be at risk for ovarian hyperstimulation (serum E2 levels >2,500 pg/mL or >20 follicles at the time of hCG administration). INTERVENTION(S): Gonadotropin administration was withheld when serum E2 levels exceeded 2,500 pg/mL, and hCG administration was delayed until E2 levels dropped below 2,500 pg/mL. Outcomes were compared with those from 120 matched patients in whom serum E2 levels and the number of follicles at the time of hCG administration were comparable to those at the beginning of coasting (control group). MAIN OUTCOME MEASURE(S): Incidence of moderate and severe OHSS. The number of oocytes retrieved and pregnancy rate (PR) were compared in both groups. RESULT(S): Coasting decreased the incidence of moderate and severe OHSS. The odds ratio of severe OHSS in the coasting group was 0.11 (95% confidence interval 0.01-0.86). Although the number of oocytes was significantly lower in the coasting group (19.7 +/- 0.6 versus 22.1 +/- 0.6), coasting did not affect the PR (37.5% versus 36.7%). CONCLUSION(S): Our study indicates that coasting is an efficient method for reducing the incidence and severity of OHSS without compromising the PR.

Adult↗
PubMed1998

Fluorescent in-situ hybridization on human embryos showing cleavage arrest after freezing and thawing.

Our current freezing-thawing policy is to transfer only embryos that cleave further in the 24 h following thawing. The purpose of our study was to investigate the incidence of numerical abnormalities for chromosomes X, Y and 1 in blastomeres of human preimplantation embryos that survived cryopreservation but did not cleave further after thawing. A total of 63 embryos surviving a freezing-thawing cycle but not cleaving further within 24 h after thawing were screened. Of the 63 screened embryos that showed cleavage arrest 24 h after thawing, 56 embryos (88.9%) remained arrested 48 h after thawing and slightly more than half of these (29/56; 51.8%) showed further deterioration in morphological quality. Seven embryos (11.1%) showed signs of further cleavage; five embryos showed additional cleavage of one blastomere and two developed a blastocoelic cavity. Fluorescent in-situ hybridization (FISH) with three specific probes for simultaneous detection of chromosomes X, Y and 1 was performed and was successful in 60 out of 63 embryos. Of these successfully labelled embryos, 26 (43.3%) were in the diploid range: 12 (20%) were uniformly diploid for the chromosomes X, Y and 1; three embryos showed aneuploidy in all their blastomeres (two were XXY-karyotype and one was monosomy 1) and in 11 embryos nondisjunction was detected. Thirteen embryos were categorized as being either haploid, triploid, tetraploid or hexaploid. Nine embryos were classified as mosaic and 12 as being highly abnormal or chaotic. These preliminary results suggest that a large proportion of embryos that do not cleave further after freezing and thawing carry chromosomal aberrations. This finding supports our policy of not transferring cryopreserved embryos which do not cleave further 24 h following thawing.

Aneuploidy↗
PubMed1998

Embryos cultured in vitro with multinucleated blastomeres have poor implantation potential in human in-vitro fertilization and intracytoplasmic sperm injection.

The aim of the present study was to investigate pregnancy rates ensuing from transfer of embryos with multinucleated blastomeres. In our in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) programme, 1735 embryo transfers were performed from January 1, 1995 to August 31, 1996. In 136 of these transfers at least one embryo with one or more multinucleated blastomeres was present per transfer (study group). For each of these 136 transfers, two matched controls with transfer of exclusively mononucleated embryos were selected (control group). Matching was carried out according to age, method of fertilization (IVF or ICSI), number of transferred embryos and quality score of transferred embryos. In the study group, there were eight transfers of exclusively multinucleated embryos from which one pregnancy ensued and 128 transfers in which multinucleated and mononucleated embryos were transferred together leading to 23 pregnancies. The overall clinical pregnancy rate per transfer was 16.9% in the study group versus 28.7% in the control group (P = 0.01). The ongoing pregnancy rate per transfer was 13.2% in the study group versus 23.2% in the control group (P = 0.03). The implantation rate per transferred embryo was 6.0% in the study group versus 11.3% in the control group (P = 0.003). This study shows that embryos with one or more multinucleated blastomeres have a poorer implantation potential than embryos with mononucleated blastomeres. Transfer of embryos with multinucleated blastomeres should hence only be considered when insufficient numbers of embryos with only mononucleated blastomeres are present.

Adult↗