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Biomedical subjects

Jan Tesarik

Publications and source records attributed to Jan Tesarik.

At least 19 recordsLinked to original sources
PubMed2006

Beneficial effect of luteal-phase GnRH agonist administration on embryo implantation after ICSI in both GnRH agonist- and antagonist-treated ovarian stimulation cycles.

BACKGROUND: GnRH agonist was recently suggested as a novel luteal-phase support that may act at different levels, including the pituitary gonadotrophs, the endometrium and the embryo itself. This prospective randomized study evaluates the effect of GnRH agonist administered in the luteal phase on ICSI outcomes in both GnRH agonist- and GnRH antagonist-treated ovarian stimulation protocols. METHODS: Six hundred women about to undergo ovarian stimulation for ICSI (300 using a long GnRH agonist protocol and 300 using a GnRH antagonist protocol) were enrolled in this study. Patients treated with each of these two protocols were randomly assigned to receive a single injection of GnRH agonist or placebo 6 days after ICSI. Implantation and live birth rates were the primary outcomes. RESULTS: Administration of 0.1 mg of GnRH agonist triptorelin on day 6 after ICSI led to a significant improvement of implantation and live birth rates after ICSI as compared with placebo. In GnRH antagonist-treated ovarian stimulation cycles, luteal-phase GnRH agonist also increased ongoing pregnancy rate. Moreover, luteal-phase GnRH agonist administration increased luteal-phase serum HCG, estradiol and progesterone concentrations in both ovarian stimulation regimens. CONCLUSIONS: Luteal-phase GnRH agonist administration enhances ICSI clinical outcomes after GnRH agonist- and GnRH antagonist-treated ovarian stimulation cycles, possibly by a combination of effects on the embryo and the corpus luteum.

Adult↗
PubMed2006

Limiting the number of injected oocytes to three impairs ICSI outcomes in patients with nonobstructive azoospermia.

BACKGROUND: Since March 2004, only a maximum of three oocytes were allowed to be subjected to ICSI at one time in Italy. A previous study failed to show an impact of this restriction on fresh embryo transfer outcomes. The objective of this study was to compare ICSI outcomes before and after this restriction in patients with nonobstructive azoospermia. METHODS: Patients underwent testicular sperm extraction followed by ICSI. Biological (fertilization rate and the percentage of good-morphology zygotes and embryos) and clinical (clinical pregnancy and implantation rates) outcomes of the last 100 ICSI attempts before the restriction and outcomes of the first 100 ICSI attempts after the restriction were compared. RESULTS: Despite comparable fertilization rates (58.8% versus 59.2%; P > 0.05), there was a significant decrease in the percentage of good-morphology zygotes (41.1% versus 88.4%; P < 0.05) and embryos (36.7% versus 74.0%; P < 0.05) in the cohort of embryos transferred, clinical pregnancy rate (22.7% versus 42.4%; P < 0.05) and cumulative pregnancy rate from fresh and frozen embryo transfers (22.7% versus 53.5%; P < 0.05) after the restriction. CONCLUSION: The oocyte number restriction reduces dramatically the chance of achieving a clinical pregnancy in cases of nonobstructive azoospermia.

Adult↗
PubMed2006

High-magnification ICSI overcomes paternal effect resistant to conventional ICSI.

Previous studies have shown that repeated intracytoplasmic sperm injection (ICSI) failures can be caused by a paternal effect. Other studies have suggested that ICSI results are compromised if morphologically abnormal spermatozoa are injected into oocytes. This study was undertaken to evaluate the usefulness of a high-magnification optical system to select spermatozoa to be used for ICSI (high-magnification ICSI) in couples with repeated conventional ICSI failures. Couples with two or more previous conventional ICSI failures underwent an additional conventional ICSI attempt, followed by a high-magnification ICSI attempt. The outcomes of the two sequential attempts were compared. In 72 of these patients, sperm DNA integrity was assessed. In the whole group of 125 couples with repeated ICSI failures, high-magnification ICSI improved clinical outcomes (pregnancy, implantation, delivery and birth rates) without affecting biological outcomes (fertilization and cleavage rates, embryo morphology). The improvement of clinical ICSI outcomes was evident both in patients with an elevated degree of sperm DNA fragmentation and in those with normal sperm DNA status. It is concluded that high-magnification ICSI improves clinical outcomes in couples with previous repeated conventional ICSI failures.

Adult↗
PubMed2006

Sperm nuclear DNA damage: update on the mechanism, diagnosis and treatment.

Previous studies have shown that repeated intracytoplasmic sperm injection failures can be associated with sperm DNA damage. This paper reviews the current understanding of the mechanism of sperm DNA damage, discusses different diagnostic methods and their threshold values to discriminate between good- and poor-prognosis patients, and outlines the currently available treatment options. A rational approach to the interpretation of sperm DNA fragmentation data and to the choice of the optimal treatment method is suggested.

Antioxidants↗
PubMed2005

ICSI in cases of sperm DNA damage: beneficial effect of oral antioxidant treatment.

BACKGROUND: Most studies examining the use of ICSI for cases of elevated sperm DNA fragmentation report poor pregnancy and implantation rates. ICSI with testicular sperm samples has recently been suggested for these cases. Here we test a less invasive approach based on oral antioxidant treatment prior to ICSI with ejaculated spermatozoa. METHODS: Thirty-eight men with an elevated (> or =15%) percentage of DNA-fragmented spermatozoa in the ejaculate were treated with antioxidants (1 g vitamin C and 1 g vitamin E daily) for 2 months after one failed ICSI attempt. In 29 (76%) of these cases this treatment led to a decrease in the percentage of DNA-fragmented spermatozoa, and a second ICSI attempt was performed. Outcomes of the two attempts were compared. RESULTS: No differences in fertilization and cleavage rates or in embryo morphology were found between the ICSI attempts performed before and after the antioxidant treatment. However, a marked improvement of clinical pregnancy (48.2% versus 6.9%) and implantation (19.6% versus 2.2%) rates was observed after the antioxidant treatment as compared with the pretreatment ICSI outcomes. CONCLUSIONS: Oral antioxidant treatment appears to improve ICSI outcomes in those patiens with sperm DNA damage, in whom this treatment reduces the percentage of damaged spermatozoa.

Adult↗
PubMed2005

Improvement of delivery and live birth rates after ICSI in women aged >40 years by ovarian co-stimulation with growth hormone.

BACKGROUND: Growth hormone (GH) is required for ovarian follicular development, and its administration during ovarian stimulation improves pregnancy rate in cow and sheep. Data on the use of exogenous GH in human assisted reproduction treatment are inconsistent. This prospective randomized study evaluates the usefulness of GH administration in women of >40 years undergoing ovarian stimulation for assisted reproduction treatment. METHODS: One hundred women of >40 years undergoing assisted reproduction treatment were randomized between a GH treatment group and a placebo group. Assisted reproduction treatment outcomes were evaluated. RESULTS: In patients of the GH treatment group, a similar number of oocytes, embryos and pregnancies was achieved as compared with the placebo group. However, the patients treated with GH suffered fewer pregnancy losses, resulting in higher delivery and live birth rates. These patients also showed higher peak serum estradiol concentration and higher concentrations of GH and estradiol in pre-ovulatory follicular fluid as compared with the placebo group. CONCLUSIONS: Administration of GH during ovarian stimulation alleviates age-related decrease in assisted reproduction treatment efficiency. This effect appears to be mainly due to an improvement of oocyte developmental potential, but GH action on the uterus cannot be excluded.

Adult↗
PubMed2005

Novel concepts of human chorionic gonadotropin: reproductive system interactions and potential in the management of infertility.

OBJECTIVE: To extensively review the scientific literature on the potential sites of hCG action and the role of this hormone on reproductive processes not necessarily related to the classic hCG functions of supporting early pregnancy. DESIGN: Review of the international scientific literature and the authors' personal research experience in this area. RESULT(S): The LH/hCG receptor has an almost ubiquitous distribution in reproductive organs, thus suggesting that the actions of hCG might be more extensive than previously thought. Independently of FSH, low-dose hCG can support development and maturation of larger ovarian follicles that have acquired granulosa cells LH/hCG receptors, potentially providing effective and safer ovulation induction regimens. Human chorionic gonadotropin seems to be capable of improving uterine receptivity by enhancing endometrial quality and stromal fibroblast function. Furthermore, through its actions on insulin-like growth factor binding protein-1 and vascular endothelial growth factor, hCG might stimulate endometrial angiogenesis and growth and extend the implantation window, thus making pregnancy more likely. CONCLUSION(S): Mounting evidence indicates that hCG could be mediating relevant actions enhancing fertility and the efficacy of therapeutic procedures used in the management of infertility. Greater understanding of the physiologic roles that hCG plays in human reproduction might suggest novel clinical applications for this traditional hormone of pregnancy.

Animals↗
PubMed2005

Developmental potential of fully intact and partially damaged cryopreserved embryos after laser-assisted removal of necrotic blastomeres and post-thaw culture selection.

OBJECTIVE: Partially damaged frozen and thawed embryos are currently considered to have a lower viability than intact ones. This study was undertaken to compare the performance of intact frozen and thawed embryos with that of partially damaged embryos after removal of the necrotic blastomeres. DESIGN: Observational clinical series. SETTING: Private hospital. PATIENT(S): Three hundred twenty-six infertile couples undergoing frozen embryo transfer. INTERVENTION(S): Removal of necrotic blastomeres from frozen-thawed human embryos. MAIN OUTCOME MEASURE(S): Pregnancy and implantations rates. RESULT(S): Outcomes of frozen embryo transfer cycles in which all embryos were fully intact (group 1) were compared with those in which all embryos have lost 1-2 blastomeres (group 2) or 3-4 blastomeres (group 3). Laser-assisted hatching was performed in all embryos, and necrotic blastomeres were removed from partially damaged embryos on this occasion. Only embryos that resumed mitotic activity after thawing were transferred. Comparable clinical pregnancy rates (PR) (38.7%, 39.6%, and 29.4%), delivery rates (34.4%, 34.0%, and 29.4%), and implantation rates (21.6%, 21.4%, and 17.2%) were obtained in groups 1, 2, and 3, respectively. CONCLUSION(S): The developmental potential of partially damaged frozen and thawed embryos can be equivalent to fully survived embryos if the necrotic blastomeres are removed from the partially damaged embryos and only those of them that show post-thaw cleavage are selected for transfer.

Adult↗
PubMed2005

Paternal effects on cell division in the human preimplantation embryo.

Cell divisions in the human preimplantation embryo can be compromised by deficiencies in sperm nuclear genome or sperm-derived developmentally relevant cytoplasmic factors, oocyte activating substance and centriole. Sperm nuclear deficiencies are usually not detected before the 8-cell stage of embryo development, when a major expression of sperm-derived genes has begun. Sperm cytoplasmic deficiencies can be detected as early as the 1-cell zygote and then throughout the preimplantation development. The terms 'late paternal effect' and 'early paternal effect' have been suggested to denote these two pathological conditions. The late paternal effect is associated with an increased incidence of sperm DNA fragmentation. No association with sperm DNA damage has been found for the early paternal effect. The diagnosis of the late paternal effect is thus based on the examination of sperm DNA integrity, which should be performed in cases of repeated assisted reproduction failure even if morphologically normal embryos result from fertilization with the patient's spermatozoa. The only element leading to the diagnosis of the early paternal effect is poor zygote and embryo morphology and low cleavage speed. The absence of increased sperm DNA damage does not exclude the presence of this pathology. ICSI with testicular spermatozoa has recently been shown to be an efficient treatment for the late paternal effect. The use of oral antioxidant treatment in this indication has also given promising results.

Blastocyst↗
PubMed2004

Efficient treatment of infertility due to sperm DNA damage by ICSI with testicular spermatozoa.

BACKGROUND: Sperm DNA damage (fragmentation) is a recently discovered cause of male infertility for which no efficient treatment has yet been found. Previous findings have suggested that clinically relevant sperm DNA damage may occur at the post-testicular level. This study was undertaken to assess the clinical usefulness of ICSI with testicular spermatozoa in this indication. METHODS: The percentage of spermatozoa with fragmented DNA, assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labelling assay, and ICSI outcomes were compared in two sequential attempts performed, respectively, with ejaculated and testicular spermatozoa in 18 men with increased sperm DNA fragmentation. RESULTS: The incidence of DNA fragmentation was markedly lower in testicular spermatozoa as compared with ejaculated spermatozoa. No differences in fertilization and cleavage rates and in embryo morphological grade were found between the ICSI attempts performed with ejaculated and with testicular spermatozoa. However, eight ongoing clinical pregnancies (four singleton and four twin) were achieved by ICSI with testicular spermatozoa (44.4% pregnancy rate; 20.7% implantation rate), whereas ICSI with ejaculated spermatozoa led to only one pregnancy which was spontaneously aborted. CONCLUSIONS: These data show that ICSI with testicular spermatozoa provides the first efficient assisted reproduction treatment option for men with high levels of sperm DNA damage.

Adult↗
PubMed2004

Enhancement of embryo developmental potential by a single administration of GnRH agonist at the time of implantation.

BACKGROUND: Several reports have shown that inadvertent administration of a GnRH agonist in the luteal phase does not compromise pregnancy. Moreover, some studies suggested that, unexpectedly, the embryo developmental potential is improved in these conditions. This prospective controlled study was designed to test this hypothesis. METHODS: In an oocyte donation programme, oocytes from each donor (n = 138) were shared by two recipients, one of whom was given a single dose of a GnRH agonist (0.1 mg triptorelin) 6 days after ICSI, and the other received placebo at the same time. RESULTS: Oocyte recipients treated with GnRH agonist 6 days after ICSI had higher implantation (36.9 versus 25.1%), twin pregnancy (16.7 versus 3.6%), twin delivery (13.8 versus 2.2%) and birth (31.1 versus 21.5%) rates and similar miscarriage and abortion rates as compared with the placebo group. CONCLUSIONS: GnRH agonist administration at the time of implantation enhances embryo developmental potential, probably by a direct effect on the embryo.

Adult↗
PubMed2004

Late, but not early, paternal effect on human embryo development is related to sperm DNA fragmentation.

BACKGROUND: It is known that repeated failure of assisted reproduction treatment (ART) can be due to a paternal effect. This study was undertaken to analyse the possible relationship between ART failure and sperm DNA fragmentation. METHODS: Zygote morphology and the percentage of spermatozoa with fragmented DNA (assessed by TUNEL) were compared in two groups using donor oocytes for ICSI attempts. The experimental group consisted of 18 infertile couples who had each undergone three previous failed ART attempts. The control group included 18 randomly selected infertile couples undergoing their first ICSI attempt. Both groups used sibling oocytes from the same donors. RESULTS: In 10 couples of the experimental group, the adverse paternal effect was evident as early as the zygote stage. This early paternal effect was not associated with sperm DNA fragmentation. In eight couples of the experimental group, the adverse paternal effect did not produce any perceptible deterioration of zygote morphology. However, this late paternal effect was associated with an increased percentage of spermatozoa with fragmented DNA. CONCLUSIONS: Early paternal effect can compromise ART outcomes in the absence of increased sperm DNA fragmentation. Evaluation of sperm DNA integrity is useful to detect late paternal effect, which is not associated with morphological abnormalities at the zygote and early cleavage stages.

DNA Fragmentation↗
PubMed2004

Apoptosis and necrosis in human ejaculated spermatozoa.

BACKGROUND: Features of both apoptosis and necrosis have been reported in ejaculated human spermatozoa. This study examines the relative contribution of these two modes of cell death to the demise of these terminally differentiated cells. METHODS: Sperm fractions were prepared from aliquots of semen samples from young normozoospermic donors by simple washing from seminal plasma, by discontinuous density gradient centrifugation or by swim-up technique. They were subsequently incubated in vitro at 37 degrees C for 24 h. Sperm motility, viability, and the presence of two apoptotic markers, phosphatidylserine externalization (annexin-V binding) and DNA fragmentation (TUNEL), were examined before incubation and again after 4 and 24 h of incubation. RESULTS: The swim-up technique was the most efficient in terms of the recovery of viable, motile and non-apoptotic spermatozoa, followed by density gradient centrifugation and finally simple washing. No changes in the parameters tested were observed after 4 h of incubation, but a significant decrease in sperm motility and viability was detected after 24 h irrespective of the sperm preparation technique employed. However, these changes were not accompanied by any increase in the incidence of spermatozoa showing markers of an active apoptotic process. CONCLUSIONS: Healthy human ejaculated spermatozoa appear incapable of initiating apoptosis, at least under in vitro conditions.

Adult↗
PubMed2004

Overcoming maturation arrest by in vitro spermatogenesis: search for the optimal culture system.

In some men with nonobstructive azoospermia caused by germ cell maturation arrest, spermatogenesis can be reactivated in vitro, either by culturing segments of explanted seminiferous tubules or by coculturing isolated germ cells on monolayers of somatic cell lines. Further studies are needed to compare the efficacy of these two culture systems in terms of restoration of fertilizing ability of in vitro-formed gametes and to evaluate the safety of the clinical use of these cells in assisted reproduction treatment.

Animals↗
PubMed2004

Pronuclear morphology predicts embryo development and chromosome constitution.

The relationship between pronuclear morphology on the one hand, and embryo development and chromosomal status on the other, was evaluated in 68 couples scheduled to undergo preimplantation genetic diagnosis because of advanced maternal age or recurrent implantation failure. Zygotes were grouped according to their pronuclear (PN) morphology. During the period from fertilization to embryo transfer, cleavage rate, embryo quality, blastocyst formation and results of the chromosomal analysis of 240 embryos were recorded. Both embryo cleavage characteristics and chromosome constitution were related to PN morphology. Embryos developing from zygotes with the normal PN pattern (pattern 0) cleaved faster and formed embryos with better morphology as compared with zygotes with abnormal PN patterns. Aneuploidy rate of embryos derived from zygotes with the normal PN pattern, with a single PN anomaly and with a double PN anomaly was 25.6, 73 and 83% respectively. Chromosomally normal embryos with the normal PN pattern progressed to the blastocyst stage at a higher rate (90%) than chromosomally normal embryos with a single (61%) or a double (40%) PN anomaly. The same relationship applied to chromosomally abnormal embryos. It is concluded that PN morphology predicts both the risk of embryo developmental arrest and that of chromosomal abnormalities.

Blastocyst↗
PubMed2004

A zygote is not an embryo: ethical and legal considerations.

In spite of several past attempts at defining the point at which conception can be considered completed, resulting in the formation of an embryo, the existing definitions are still contradictory. In the absence of clear terminology, the application of laws aimed at the protection of early human life may have inadequate consequences for the efficacy of the current techniques of human infertility treatment. In this paper biological arguments are revisited, suggesting that the only point at which a clear demarcation line between what is and what is still not an embryo can be drawn is the moment of nuclear syngamy at the outset of the first cleavage division. The term 'zygote' is suggested to denote entities composed of spermatozoon and oocyte components before nuclear syngamy. It is suggested that the current embryo protection laws should not concern the zygote stage: at this stage, the main features that are said, in documents issued by different ethical and legal authorities, to characterize the early human embryo, namely the inseparable union of the male and female contribution, cell division and an autonomous control over cell division, are still not present. This reasoning strictly applies to embryos of biparental (paternal and maternal contribution) origin and cannot be extrapolated to embryos created by cell nuclear transfer (cloning). The application of embryo protection laws from the nuclear syngamy stage onwards can regulate embryo and embryo-derived stem cell research while still preserving the current high standard and efficacy of infertility treatment, which is of immediate interest to millions of infertile couples throughout the world.

Blastocyst↗
PubMed2004

Caspase-dependent and -independent DNA fragmentation in Sertoli and germ cells from men with primary testicular failure: relationship with histological diagnosis.

BACKGROUND: Germ cell elimination and sperm DNA fragmentation in men with primary testiculopathies involve apoptosis-related processes whose mechanisms are poorly understood. This study examines the participation of typical (caspase-dependent) and atypical (caspase-independent) pathways in these processes. METHODS: Caspase activity and DNA fragmentation were evaluated in Sertoli and germ cells from 63 men with non-obstructive azoospermia and with different histological diagnoses who were undergoing testicular biopsy for an assisted reproduction attempt. In eight of these men, phosphatidylserine externalization was also examined. RESULTS: The percentage of Sertoli cells showing caspase activity and DNA fragmentation was low and uniform in all diagnoses. In germ cells that remained tightly associated with Sertoli cells despite vigorous mechanical treatment, the incidence of both caspase activity and DNA fragmentation was high, particularly in men with maturation arrest. In Sertoli cell-free germ cells, high incidence of DNA fragmentation contrasted with low incidence of caspase activity and phosphatidylserine externalization. CONCLUSIONS: In men with primary testicular failure, apoptosis of Sertoli cells is insignificant. Some germ cells undergo caspase-dependent apoptosis, show phosphatidylserine externalization and are tightly associated with Sertoli cells. Other germ cells show caspase-independent DNA fragmentation, do not externalize phosphatidylserine and lack a tight association with Sertoli cells.

Apoptosis↗