SEARCH · PubMed Health

Results for “Reproductive Techniques, Assisted”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources

PubMed1998

Cryopreservation of non-human primate sperm: priorities for future research.

Wild populations of many non-human primate species have declined alarmingly due to habitat destruction, hunting and genetic isolation. Captive breeding programmes to aid species survival could be enhanced by the use of assisted reproductive techniques, such as artificial insemination (AI), if a source of viable sperm was readily accessible. Cryobanks of primate sperm could provide such a supply if techniques for freezing sperm could be developed. Although sporadic attempts to cryopreserve primate sperm have been reported for some of the more frequently encountered zoo-maintained species, there is limited information available on techniques for sperm collection and storage. It is vital that adequate reporting of all cryopreservation attempts be made to avoid repetition of inappropriate methodologies and wastage of valuable genetic material from rare or endangered animals. An integrated approach to the cryobanking of non-human primate sperm is considered to be essential for species conservation. In this review, the factors affecting the success of sperm cryopreservation are outlined, existing information is compiled from previous reported attempts at cryopreservation, and suggestions are made for cryopreserving sperm in further non-human primate species. Moreover, recommendations are given for additional studies to augment existing data. It is intended that this information should serve as a guide for developing cryopreservation protocols in the future, particularly for endangered species.

Animals↗

PubMed1998

The impact of age on reproductive potential: lessons learned from oocyte donation.

OBJECTIVE: Oocyte donation allows a unique opportunity to separately study the effect of aging on uterine receptivity and oocyte quality. The purpose of this report is to review the published experience on reproductive aging in both laboratory animals and humans as it pertains to oocyte and embryo donation. METHODS: A review of the published medical literature. RESULTS: Natural fertility rates decline in most animals with age, becoming dramatically apparent in women as they enter the fifth decade of life. By the time of the perimenopause, pregnancy rarely occurs, whether or not assisted reproductive techniques are initiated. However, if oocytes are donated by young women to older women, both embryo implantation and pregnancy rates are restored to normal levels in recipients. CONCLUSIONS: These results strongly suggest the pregnancy wastage experienced by older women is largely a result of degenerative changes within the aging oocyte, rather than senescent changes in the uterus. The poor prognosis for fertility in older women can be reversed through oocyte donation from younger individuals.

Age Distribution↗

PubMed1996

Early embryonic development and evaluation of equine embryo viability.

Tremendous progress has been made in the development of assisted reproductive techniques that may enhance the reproductive efficiency of the horse. However, techniques that involve the manipulation of oocytes and/or embryos may themselves be detrimental to embryo viability and subsequent development. Therefore, an objective method of assessing viability of embryos before and/or after oocyte/embryo manipulation is desirable. At this time, morphologic evaluation is the most widely used method of determining the viability of equine embryos. Although morphologic assessment of embryo quality will not always accurately predict the survival of individual embryos, it is very useful for predicting the survival of groups of embryos. Other tests that have been used to evaluate equine embryo viability include (1) development during culture in vitro; (2) quantitating metabolism of the fluorescent substrate fluorescein diacetate; (3) quantitating uptake of the fluorescent stain DAPI; and (4) quantitating embryo metabolism. Although these tests offer potential advantages over morphologic assessment alone, their current limitations have prevented their routine use for embryo evaluation. It is likely that as improvements are made in these evaluation methods, they may offer advantages for use alone or in combination to more accurately assess the viability of equine embryos.

Animals↗

PubMed2006

[Knowledge of legal aspects of organ donation by live donors. Staff survey at a university hospital center].

OBJECTIVE: Law no. 2004-800 dated August 6, 2004, establishes new legal measures to facilitate live organ donation, in view of the shortage of organs for transplantation. We sought to assess the knowledge of this statute among hospital personnel. METHOD: We sent an e-mail questionnaire to 1015 persons working at Amiens university hospital center. It contained eleven closed questions (yes/no/don't know) about permissible live organ and tissue donation and two questions requesting personal opinions about live donation. We compared responses according to profession and department. RESULTS: Questionnaires were returned by 245 respondents. The questions for which more than 70% provided correct answers concerned the fundamental principles of bioethics (consent revocable at any time, donations by adults, donations between spouses, bone marrow donations by minors). Fewer than half the respondents knew the correct answers about the new legal measures adopted in the statute (extension of the circle of potential donors, possible exceptions for donations by minors and incompetent adults). Knowledge of the law concerning assisted reproduction techniques was much poorer: fewer than 30% knew that sperm or oocyte donation requires spousal consent. Three quarters of the respondents have discussed their wishes with their family; 65% would provide a live kidney donation, although some only for a family member. In all 31% have organ donor cards. DISCUSSION: Donations by live donors raise psychological as well as ethical and legal issues. This survey increased the awareness of hospital staff, provided them with information about the relevant law and, we hope, stimulated their thinking about the topic of live donations.

France↗

PubMed2001

Pregnancy outcomes in women with congenital virilizing adrenal hyperplasia.

Although low fertility rates have traditionally been reported among women with classic CAH and especially among women with the salt-wasting variant, more recent data suggest that fertility rates are significantly improved, largely owing to earlier treatment of CAH, improved compliance with therapy, and surgical advances in genital reconstruction. Furthermore, ovulation induction and assisted reproductive techniques are now available to women who remain infertile despite effective adrenal androgen suppression. Although the pregnancy experience in women with classic CAH remains limited, it is apparent that, once pregnant, these women have a high probability of successful outcome. Key issues should be emphasized in the management of CAH during gestation, including the need for assessing adrenal steroid replacement and adrenal androgen suppression, particularly in light of the interplay between maternal hyperandrogenism and the protective effect of placental aromatase activity, which provides a relatively large margin of safety for the female fetus. Maternal hormone levels should be evaluated in the context of laboratory-specific reference ranges for pregnancy. The infant should be examined for ambiguous genitalia and monitored for evidence of adrenal insufficiency. Although an affected female infant with classic CAH has not been reported as a pregnancy outcome of a mother with classic virilizing CAH, these concerns should be discussed during preconception counseling. Patients should also be aware of the importance of medication compliance and careful hormonal monitoring during the entire pregnancy. In most cases, successful gestational management requires the close coordination of care between the obstetrician and endocrinologist.

Adrenal Hyperplasia, Congenital↗

PubMed1998

The use of gonadotrophin-releasing hormone antagonists in polycystic ovarian disease.

Polycystic ovarian disease (PCOD) is characterized by anovulation, eventually high luteinizing hormone (LH) levels, with increased LH pulse frequency, and hyperandrogenism. As the aetiology of the disease is still unknown, gonadotrophin-releasing hormone (GnRH) antagonists, competitive inhibitors of GnRH for its receptor, are interesting tools in order to study and treat the role of increased LH levels and pulse frequency in this disease. Their administration provokes a rapid decrease in bioactive and immunoactive LH followed by a slower decrease in follicle-stimulating hormone (FSH). In patients with PCOD, the suppression of gonadotrophin secretion eradicates the symptoms of the disease as long as the treatment lasts. Several authors have suggested that increased plasma LH levels have deleterious effects on the fertility of women with PCOD. Indeed, fewer spontaneous pregnancies with more miscarriages are observed when plasma LH levels are high. Assisted reproduction techniques such as in vitro fertilization (IVF) have provided other clues to the role of the LH secretory pattern in women with PCOD. The number of oocytes retrieved, the fertilization rate and the cleavage rate are lower in PCOD patients undergoing IVF and this is inversely correlated with FSH:LH ratio. These abnormalities are corrected when endogenous secretion of LH is suppressed. On the other hand, implantation and pregnancy rates after IVF are similar to those observed in control women. New GnRH antagonists are devoid of side effects and suppress LH secretion within a few hours without a flare-up effect. This action lasts for 10-100 hours. When GnRH antagonists are associated with i.v. pulsatile GnRH, this combination both suppresses the effect of endogenous GnRH and because of the competition for GnRH receptors restores a normal frequency of LH secretion. We have studied two women with PCOD, administering first 10 mg s.c. every 72 hours for 7 days of the GnRH antagonist Nal-Glu, then adding on top i.v. pulsatile GnRH: 10 micrograms/pulse every 90 minutes for 15 days. We thus succeeded in normalizing LH secretion pattern and observed a significant decline in testosterone levels. We failed to induce appropriate ovarian response and ovulation. In conclusion, the combination of GnRH antagonist and GnRH pulsatile treatment can re-establish normal LH secretory pattern in patients with PCOD. The failure to induce ovulation with this regimen suggests the existence of an inherent ovarian defect in women with PCOD.

Adult↗

PubMed2003

[Evaluation of the interest of semen culture before cryoconservation].

OBJECTIVES: French guidelines recommend screening all patients for virus infection prior to cryopreservation of their semen. In case of viral risk, the use of specific high secure CBS straws is recommended. The objective of this work was to evaluate the microbiological risk by testing all semen samples before cryopreservation. PATIENTS AND METHODS: Fifty one patients underwent a semen culture before cryopreservation. RESULTS: The fifty one patients were classed into 3 groups following semen culture results: group I: negative culture (39/51, 76.47%), group II: positive culture with microbiological contamination (7/51, 13.73%) and group III: positive culture with pathogen (5/51, 9.8%). For 3 patients of the latter group, we tested a three-layer density gradient to eliminate bacteria before Assisted Reproductive Techniques. DISCUSSION AND CONCLUSIONS: This paper discusses the risks related to microbiological contamination and the options available in this case.

Bacterial Infections↗

PubMed2004

Unsuccessful oocyte retrieval: technical artefact or genuine 'empty follicle syndrome'?

Unsuccessful oocyte retrieval after apparently successful ovarian stimulation (also referred to as 'empty follicle syndrome') occurs in 1-7% of women undergoing assisted reproductive techniques. A literature review was performed, as individual studies have reached differing conclusions on the aetiology and treatment or management of the phenomenon. The aetiology is not clear, but probably multifactorial, and occurs in natural and stimulated cycles. In many cases, technical problems such as errors in human chorionic gonadotrophin (HCG) administration or defects in HCG batches can be identified, but this is not sufficient to account for all reported cases. The term empty follicle syndrome is inappropriate in cases in which such procedural factors can be identified. In many patients, however, unsuccessful oocyte retrieval appears to be due to an underlying ovarian dysfunction, and some may have a genuine empty follicle syndrome. Appropriate measures, such as monitoring of serum beta-HCG, should be taken to minimize the risk of unsuccessful oocyte retrieval. This review discusses the potential causes of unsuccessful oocyte retrieval, its clinical implications, and potential solutions to this clinical problem.

Artifacts↗

PubMed2006

FSH and folliculogenesis: from physiology to ovarian stimulation.

FSH is a glycoprotein hormone consisting of two peptide subunits. The role of FSH in folliculogenesis is well known: to stimulate the formation of a large pre-ovulatory follicle that, because of its FSH-dependent maturation, is capable of ovulation and forming a corpus luteum in response to the mid-cycle surge of LH. FSH is widely used in ovarian stimulation for assisted reproduction techniques. Ovarian stimulation protocols combine the use of human menopausal gonadotrophin, urinary FSH or recombinant FSH with gonadotrophin-releasing hormone (GnRH) agonists or antagonists in order to increase oocyte number and to avoid premature LH surge. Recently, the availability of recombinant LH has permitted new stimulation protocols, combining recombinant FSH, recombinant LH and GnRH antagonists. Due to the limitations of the new Italian law in terms of the number of oocytes that can be fertilized, protocols with a softer ovarian stimulation are now considered, reducing risk of ovarian hyperstimulation syndrome, multiple pregnancies and emotional and physical burdens on the patients. Long-acting FSH preparations are also under clinical study. Knowledge of the stereochemical three-dimensional structure of FSH and its receptor will allow the study of new non-peptide orally administered molecules that fit the FSH receptors.

Female↗

PubMed2006

Observations on intrauterine oxygen tension measured by fibre-optic microsensors.

Understanding the biology of reproductive organs is essential for the development of assisted reproductive techniques. There is at present no direct evidence for either the concentration and dynamics of intrauterine oxygen tension at the endometrial surface, nor its importance for the receptiveness of the endometrium. In this study a new method measured mid-cycle (ranging from day 12-18) endometrial surface oxygen tension in 21 patients referred to intrauterine insemination (IUI). Time series was measured online for a period of 5-10 min. The (mean) individual oxygen tension among patients varied from 4 to 27% air saturation. Overall mean oxygen tension among all patients was 11.8% air saturation. Within the same patient, considerable time-related variations were observed. Some patients exhibited rhythmic oscillations with a frequency in the order of 1 min, whereas others did not show any regular patterns. A good description of endometrial surface oxygen concentration and dynamics was thus obtained, but given the relatively small number of participants, an association with pregnancy following insemination could not be established. Further studies using this new method could elucidate the association between individual intrauterine activity, embryo implantation and endometrial surface oxygen tension.

Adult↗

PubMed2005

Establishment and characterization of new human embryonic stem cell lines.

Human embryonic stem cells (hESC), with their ability to differentiate into all cell types in the human body, are likely to play a very important therapeutic role in a variety of neurodegenerative and life-threatening disorders in the near future. Although more than 120 different human embryonic stem cell lines have been reported worldwide, only a handful are currently available for researchers, which limits the number of studies that can be performed. This study reports the isolation, establishment and characterization of new human embryonic stem cell lines, as well as their differentiation potential into variety of somatic cell types. Blastocyst-stage embryos donated for research after assisted reproductive techniques were used for embryonic stem cell isolation. A total of 31 blastocysts were processed either for immunosurgery or direct culture methods for inner cell mass isolation. A total of nine primary stem cell colonies were isolated and of these, seven cell lines were further expanded and passaged. Established lines were characterized by their cellular and colony morphology, karyotypes and immunocytochemical properties. They were also successfully cryopreserved/thawed and showed similar growth and cellular properties upon thawing. When induced to differentiate in vitro, these cells formed a variety of somatic cell lineages including cells of endoderm, ectoderm and mesoderm origin. There is now an exponentially growing interest in stem cell biology as well as its therapeutic applications for life-threatening human diseases. However, limited availability of stem cell lines as well as financial or ethical limitations restrict the number of research projects. The establishment of new hESC lines may create additional potential sources for further worldwide and nationwide research on stem cells.

Animals↗

PubMed2005

Ongoing pregnancy after ICSI of frozen-thawed PESA-retrieved spermatozoa and IVF in a controlled natural cycle.

The recovery of a mature oocyte from a natural cycle followed by IVF (nIVF) is an attractive alternative to conventional IVF, involving ovarian stimulation, in the treatment of female infertility. Similarly, surgical recovery of spermatozoa from the epididymis by percutaneous sperm aspiration (PESA) has simplified the treatment of men with obstructive azoospermia. A couple sought treatment for diminished ovarian reserve and male factor infertility using IVF. A mature oocyte was retrieved and was inseminated by intracytoplasmic sperm injection (ICSI), following recovery of spermatozoa by PESA. A good quality embryo was transferred. A viable pregnancy was confirmed by ultrasound scan. A healthy baby boy was delivered naturally at 37 weeks gestation. This study reports the first ongoing clinical pregnancy and subsequent birth resulting from ICSI of spermatozoa retrieved by PESA into an oocyte recovered during a natural cycle. The use of a combination of less invasive assisted reproductive techniques (PESA and nIVF) can overcome barriers to fertility.

Adult↗

PubMed2001

Definitions of human fertilization and preimplantation growth revisited.

Assisted reproductive techniques and the science of embryology have advanced rapidly over the last decades. The fact that social and moral objectives vary from country to country has resulted in differences not only in legislation, but also in the definition of embryological terms. Among the latest additions to the field has been nuclear transfer technology, which has led to concerns about the possibilities of human cloning. These facts call for a review of gametogenesis and early embryogenesis. The aim of the present paper is to initiate a discussion on terminology with a view to reaching a consensus. As a starting point definitions are proposed for the most important terms.

Journal Article↗

PubMed2006

Comet assay of cumulus cells and spermatozoa DNA status, and the relationship to oocyte fertilization and embryo quality following ICSI.

It has been postulated that apoptosis may affect cumulus cell and sperm DNA integrity, and therefore influence the outcome of assisted reproductive techniques. This study investigates apoptotic levels in both cumulus cells and spermatozoa, and their relationship with fertilization and embryo quality after intracytoplasmic sperm injection (ICSI). The neutral comet assay was performed on cumulus cells and semen samples from 55 couples with male factor infertility undergoing ICSI treatment. Cells were fixed in agarose on comet assay slides, lysed in a neutral buffer and submitted to electrophoresis. The cells were stained with SYBR green fluorescent dye, which binds to double-stranded DNA and upon excitation emits light. Analysis showed that there was no correlation between apoptosis levels and the outcome of ICSI (fertilization and embryo quality).

Adult↗

PubMed2003

Embryo development characteristics in Robertsonian and reciprocal translocations: a comparison of results with non-translocation cases.

The effect of translocations on embryo development was evaluated and results were compared in terms of embryo development with those of embryos obtained from standard intracytoplasmic sperm injection (ICSI) cycles. In 23 translocation carriers with 34 cycles, fertilization, pronuclear morphology scoring (PMS), developmental arrest, cleavage and blastocyst formation were evaluated and compared with embryos obtained from non-translocation cases undergoing ICSI (n = 98 cycles). In 28 cycles, preimplantation genetic diagnosis (PGD) was performed on prezygotes (first and second polar body biopsy for female carriers; n = 3) or on embryos having seven or more blastomeres (blastomere biopsy; n = 25). In six cycles for four couples, probes for translocated chromosomes were not available, so PGD could not be performed. Overall, in translocation cases, a lower fertilization rate, a higher rate of retarded embryo development, and a lower rate of blastocyst formation were observed compared with embryos of non-translocation cases. Fluorescence in-situ hybridization (FISH) analysis showed a 70.9% abnormality rate for reciprocal translocations and 55.0% for Robertsonian translocations respectively. In cases with Robertsonian and reciprocal translocation carriers, the probability of poor embryo development, which may be a result of high segregation abnormalities, may negatively affect the outcome of assisted reproductive techniques. This poor prognosis should also be considered when genetic counselling for translocation is given.

Biopsy↗

PubMed2004

Role of free radicals in female reproductive diseases and assisted reproduction.

Infertility is a common problem experienced by many couples. Numerous treatments are available for female infertility. However, in some cases, the treatment is empirical in nature because the aetiology of infertility is not fully understood. Recently, reactive oxygen species (ROS) have been shown to have an important role in the normal functioning of reproductive system and in the pathogenesis of infertility in females. Reactive oxygen species may also play a role in other reproductive organ diseases of women such as endometriosis. Oxidative stress develops when there is an imbalance between the generation of ROS and the scavenging capacity of antioxidants in the reproductive tract. It affects both natural and assisted fertility. Because assisted reproductive techniques are used extensively in the treatment of infertility, it is critical to understand the in-vitro conditions that affect fertilization and embryo development. Treatments that reduce oxidative stress may help infertile women with diseases that are caused by this imbalance. Such strategies include identifying the source of excessive generation of ROS, treating the primary cause, and in-vitro and in-vivo supplementation of antioxidants. Research is in progress to identify the mechanisms that are involved in the aetiology of female reproductive diseases caused by ROS, and to create effective strategies that can counteract oxidative stress.

Antioxidants↗

PubMed2003

Towards a single embryo transfer.

The delivery of a single, healthy child is the desired outcome of human assisted reproduction techniques. To attain this goal, there is an increasing movement toward single embryo transfer. The question is, therefore, at what stage to transfer the human embryo back to the uterus? Maximal implantation rates reported to date have come from the transfer of blastocysts (70% fetal heart rate). In any given cycle of treatment the probability of conceiving a child will be further increased by the ability to cryopreserve those embryos not transferred. It is therefore proposed that the transfer of a single blastocyst is the best treatment for most patients, given the high implantation rates of fresh transfers, and that it is now possible to cryopreserve supernumerary blastocysts effectively. The next decision is how to culture the human embryo to the blastocyst stage. The use of sequential culture media, designed not only to allow for changes in nutrient requirements and metabolism as development proceeds, but also to minimize intracellular trauma, can facilitate the development of highly viable blastocysts. Sequential culture media have been evaluated against a single-step culture system. It has been shown that sequential media (G1/G2) produce more viable blastocysts than those embryos cultured in a single medium formulation (simplex optimized medium with elevated potassium and with amino acids, KSOM(AA)) throughout the preimplantation period. Furthermore, even if KSOM(AA) is used for embryo culture, it is essential that the medium be renewed after 48 h to alleviate the toxicity associated with ammonium build-up. Of great significance, embryos cultured in sequential media G1 and G2 have the same rate of development as embryos developed in vivo.

Animals↗

PubMed2001

The role of LHRH agonists and antagonists.

Administration of GnRH analogues (agonists as well as antagonists) produces suppression of the pituitary---gonadal axis, thus inhibiting the secretion of LH, FSH and sexual steroids. For this reason, analogs are indicated in all those clinical situations where suppression of gonadotrophins (precocious puberty, contraception) or of sexual steroids (endometriosis, prostate hyperplasia, cancer, uterine fibroids) is desired. For several years GnRH agonists have been used in combination with gonadotrophins for ovarian stimulation for assisted reproduction in order to control premature LH surges and to reduce cancellation rate with improvement of the pregnancy rate per cycle. This effect is obtained after 2 weeks of agonist administration. The immediate suppression of the pituitary achieved by GnRH antagonists without an initial stimulatory effect is the main advantage of these compounds over the agonists. The prevention of a premature LH surge by GnRH antagonists can be obtained by multiple dose or by a single administration. Both protocols offer the following advantages over the agonists: they require fewer ampoules of gonadotrophins, shorter duration of stimulation, there is a preserved pituitary response to GnRH, less risk of ovarian hyperstimulation syndrome and the luteal phase seems to be more preserved. The main disadvantages of the antagonists are that they are expensive and that pregnancy rate appears to be slightly lower than with the agonists. GnRH antagonists will probably replace agonists in ovarian stimulation treatment for assisted reproduction techniques.

Journal Article↗