New challenges in human in vitro fertilization

Restoration of endocrine function and fertility with a tubo-ovarian autotransplant as the anatomical-functional unit in rabbits using a vascular microsurgical technique

Infertility has been considered a global public health problem in many countries worldwide. Our objective was to restore endocrine function and fertility in tubal-oophorectomized rabbits using an orthotopic tubal-ovarian vascularized autotransplant model as the anatomical-functional unit while employing a microvascular surgical technique. Twenty New Zealand white (NZW) sexually mature female rabbits and four male NZW rabbits of proven fertility were divided into two study groups. In group I (n = 10), a left salpingo-oophorectomy was performed. Group II (n = 10) was subjected to a bilateral salpingo-oophorectomy, plus a right orthotopic tubal-ovarian autotransplant. Our testing variables were vascular and tubal-anastomoses permeability, estradiol (E2) and progesterone (P4) serum levels, pregnancy, number of offspring, histopathological study of the uteri, fallopian tubes, and ovaries. One hundred percent immediate permeability of the tubal anastomoses was achieved, while late permeability was found to be 64%. Immediate permeability of vascular anastomoses was 90%, and late permeability was recorded at 80%. E2 serum levels in both groups at different times showed no statistically significant differences. In the case of P4, a small difference was found during pregnancy, especially greater in the control group (P < .05). In the autotransplanted group, four rabbits became pregnant (44%). Endocrine function and fertility were restored in the rabbits with the tubal-ovarian transplant as the anatomical-functional unit. The use of isotransplants and allotransplants should be considered a therapeutic alternative in the infertile woman with irreparable bilateral tubal damage, ovarian dysgenesis, surgical absence of ovaries and fallopian tubes, or when the conventional IVF/TE in these cases has been unsuccessful.

Changes in the freezing protocol for human zygotes alter embryonic development and pregnancy rates

OBJECTIVE

To determine the effect of various freezing protocols on postthaw development and pregnancy rates resulting from transfer of human zygotes.

DESIGN

Prospective study.

SETTING

Tertiary care center.

PATIENT(S)

Couples undergoing assisted reproductive technology (ART) procedures who wished to have their excess zygotes cryopreserved.

INTERVENTION(S)

We cryopreserved zygotes with one of three protocols.

MAIN OUTCOME MEASURE(S)

Post-thaw survival and development of the zygotes as well as pregnancy rate after transfer of these zygotes.

RESULT(S)

A 3-minute hold time after seeding, followed by a final preplunging temperature of -180 degrees C, resulted in a clinical pregnancy rate of 28.6%. In contrast, a 15-minute postseed hold time and a -30 degrees C final chamber temperature resulted in a 37.3% clinical pregnancy rate. When we combined the protocols to provide a 15-minute postseed holding time and a -180 degrees C before plunging into liquid nitrogen, we achieved a 69.6% clinical pregnancy rate.

CONCLUSION(S)

By increasing the postseeding hold time and decreasing the temperature of the freezing chamber before plunging the zygotes into liquid nitrogen, significant improvements can be made in postthaw development and pregnancy rates.

Preimplantation genetic diagnosis to prevent genetic disorders in children

Preimplantation genetic diagnosis (PGD) is an alternative reproductive option for couples at risk of having a child affected with a genetic disorder. Although prenatal diagnosis (PND) has been available for many years, it is not acceptable to many owing to issues relating to termination of pregnancy. PGD involves assisted-reproductive technology, even though most couples undertaking it are fertile. However, if the treatment is successful, the couple will not have to consider PND. PGD is only available at a small number of centres and for a limited number of genetic conditions. It is a complex and time-consuming procedure. The success rate is around 20%, consequently, there is a relatively low chance of success and this requires careful consideration by couples who generally can become spontaneously pregnant. However, PGD is now more widely understood and available to all at the point of referral. This article sets out to explain the PGD procedure, its implications, limitations, and regulation in the UK and to discuss associated dilemmas.

A case of forearm amputation after ovarian stimulation for in vitro fertilization-embryo transfer

OBJECTIVE

To report a case of forearm amputation after ovarian stimulation for IVF-ET.

DESIGN

Case report.

SETTING

A university hospital.

PATIENT(S)

A 41-year-old woman, who had coagulation disorder as a result of an ovarian hyperstimulation syndrome (OHSS) for IVF-ET.

INTERVENTION(S)

Retrospective evaluation of angiographic studies and surgical treatment.

MAIN OUTCOME MEASURE(S)

Medical follow-up after forearm amputation due to OHSS.

RESULT(S)

The patient underwent many cycles of IVF-ET with administration of purified FSH (75 IU 10 times per day, for 12 days) and chorionic gonadotropin (5,000 IU). The patient had a coagulation disorder as a result of OHSS, with thrombosis of the axillary vein, recurring after thromboarterectomy and leading to the paradoxical result of the amputation of an arm.

CONCLUSION(S)

An ethical evaluation of this case is mandatory, since the desire for pregnancy, the role of medical science, health, and human life itself are all factors involved.

Scientific and ethical issues of preimplantation diagnosis

Preimplantation diagnosis (PID) offers couples at high risk of having offspring affected with a genetic disorder the possibility of an early prenatal diagnosis. For many couples this approach will give the opportunity to avoid a selective termination of affected pregnancies. Substantial advances were made in PID since the report, in 1990, of the first birth obtained after PID. Yet, many technical hazards have to be solved for PID to become a standard clinical tool. The very close correlation existing between the forthcoming developments in the fields of PID and human genome mapping will improve the reliability and efficiency of genetic diagnosis. In the near future, the procedure may also become easier and safer. As a consequence, the indications for PID could be extended to other genetic defects, such as multifactorial diseases. They could also be extended to cases with no medical background, such as social gender selection or behavioural traits. In this perspective, it is now time for both the medical and scientific communities to identify the ethical issues related to these potential new indications.

What demographers can learn from fruit fly actuarial models and biology

Historically demographers have viewed the results of actuarial studies of nonhuman species, particularly those on invertebrates such as fruit flies, as largely irrelevant to investigations on human populations. In this paper I present life table data from large scale studies on the Mediterranean fruit fly, and show that they provide important insights into fundamental aspects of mortality relevant to human populations: the trajectory of mortality at older ages, sex mortality differentials, the concept of maximal life span, and demographic heterogeneity and selection. An overriding theme of the paper is the need for demographers to acquire a heightened awareness of new developments in biology including areas such as evolutionary ecology, experimental demography, and molecular medicine.

Review: preimplantation diagnosis of inherited disease

Preimplantation diagnosis of inherited diseases has become possible with the techniques of in vitro fertilization, blastomere biopsy of the 6- to 10-cell embryo and DNA analysis of the single blastomeres. Disease-free embryos are selected for transfer to the uterus, thereby avoiding the need for termination of a fetus diagnosed as affected in prenatal diagnosis in the first or early-second trimester of pregnancy. The genetic indications for preimplantation diagnosis are theoretically the same as for prenatal diagnosis, but the defects must be detectable by the polymerase chain reaction. For X-linked recessive diseases, fluorescence in situ hybridization can be used as an alternative for the selection of female embryos. So far almost 40 healthy children have been born worldwide after preimplantation diagnosis for genetic disease. The possibilities and limitations of preimplantation diagnosis, especially in prevention of inherited disease, are discussed in this review.

Nongenomic actions of progesterone on human spermatozoa

Progesterone's (P) stimulatory actions on human spermatozoa have been known for many years. P indeed appears to be the main sperm stimulator present in women's biological fluids, particularly the follicular fluid. The nongenomic nature of the biological effects of P on human spermatozoa has been demonstrated only recently. P and 17-alpha-hydroxy P have been shown to increase sperm intracellular calcium, phosphatidylinositide hydrolysis, and tyrosine phosphorylation of proteins, and to induce the acrosome reaction (AR), through a rapid, nongenomic mechanism. The effect on calcium is due to influx of the ion from the extracellular medium, as it is inhibited by the calcium chelator EGTA and appears to be mediated by P-binding sites present on the sperm surface, particularly at the head level. The nature of such binding sites has not been addressed so far, but the lack of inhibition of P action by the potent antiprogestin RU486 strongly suggests a biochemical difference from the genomic ones. Evidence exists for involvement of the phospholipid platelet-activating factor (PAF), polyamines, tyrosine kinase activation, proteases, and other factors in P-mediated calcium increase and acrosome reaction. Recent studies suggest the possibility that the sperm's response to P may be functionally related to their fertilizing ability, thus opening new perspectives in the possible development of a predictive test in the assisted reproductive techniques.

Intracytoplasmic sperm injection using immobilized or motile human spermatozoon

OBJECTIVES

To investigate the efficacy of the treatments for oocyte activation on the results of intracytoplasmic sperm injection using immobilized or motile human spermatozoa.

DESIGN

The protocol of intracytoplasmic sperm injection was divided into four groups according to the states of sperm used for microinjection and the treatment for oocyte activation. In group A, immobilized sperm is used. The oocyte is activated merely by aspiration of the cytoplasm into the pipette. In group B, immobilized sperm is used. Microinjected oocyte is treated with A23187. In group C, immobilized sperm is used. Electroporation is performed on the microinjected oocyte. In group D, motile sperm is used. The oocyte is activated merely by aspiration of the cytoplasm into the pipette.

SETTING

The Obstetrics and Gynecology Hospital, Fukushima Medical College.

PATIENTS

The subjects are the cases that had failed fertilization in standard IVF, cases of severe oligozoospermia, and cases of severe asthenozoospermia.

RESULTS

No difference was found between the groups as to the survival rate and fertilizing rates of oocytes after intracytoplasmic sperm injection. The cleavage rate of oocytes was high in order of group D, C, B, A. The cleavage rate for groups D, C, and B was significantly higher than group A. Cases of pregnancy were found in groups D and B.

CONCLUSION

Using motile sperm rather than immobilized sperm can be expected to produce better results in human ICSI. Activating oocytes positively is needed when immobilized sperm is used.

Actions of progesterone on human sperm: a model of non-genomic effects of steroids

Non-genomic actions of steroids have been extensively studied in the last few years. Among these actions, the non-genomic effect of progesterone (P) on human spermatozoa appears to be very promising, in view of the dramatic effect of this steroid on intracellular calcium, activation of tyrosine kinase, and induction of acrosome reaction. We have shown that the ability of spermatozoa to respond to P increases during the process of capacitation and is not counteracted by the P-receptor antagonist RU486 nor by the GABAA antagonists bicuculline and picrotoxin. We have also shown that P increases tyrosine phosphorylation of a sperm protein of about 97 kDa, suggesting activation of tyrosine kinase(s). In addition, we found that P induces a perturbation of sperm membrane phospholipid metabolism resulting in an increase of synthesis of platelet-activating factor and liberation of arachidonic acid. Results of these biochemical studies indicate that P is able to stimulate several signal transduction pathways in human sperm. We have also investigated responsiveness to P in sperm of oligozoospermic subjects as well as of men undergoing an in vitro fertilization (IVF) program. Our results show that the percentage increases of intracellular calcium and acrosome reaction in response to P is significantly reduced in oligozoospermic men as well as in subjects with reduced fertilization rate. Moreover, in the latter subjects response to P is highly significant correlated to fertilization rate of oocytes. These studies indicate that a biochemical alteration of sperm in their capacity to respond to P might be responsible for reduced fertilizing ability.

Normal pregnancy after preimplantation DNA diagnosis of a dystrophin gene deletion

To perform preimplantation DNA diagnosis for Duchenne muscular dystrophy (DMD) in a female carrier of a dystrophin gene deletion of exons 3-18, we developed a polymerase chain reaction (PCR)-based assay of exon 17 sequences. Exon 17 was efficiently amplified in all 50 single blastomeres of normal control embryos and in five blastomeres of one male embryo of the DMD carrier obtained after a first preimplantation diagnosis (PID) for gender determination. In ten blastomeres of another two male embryos of the DMD carrier, no PCR signals were observed, probably as a result of the deletion. After intracytoplasmic sperm injection, embryos were analysed for exon 17 and three of the four embryos showing normal PCR signals were replaced, resulting in a singleton pregnancy. Prenatal diagnosis showed a female karyotype and DNA analysis indicated that the fetus was not a DMD carrier.

Death before birth: clues from gene knockouts and mutations

A survey of mouse gene knockouts, transgene insertions and spontaneous mutations that are lethal prenatally reveals that surprisingly few developmental disturbances lead to death of the embryo and early foetus. These disturbances include failure to establish and maintain a vascular circulation, and failure to make the transition from yolk-sac-based to liver-based haematopoiesis. The embryo must also establish gestation-dependent routes of nutritional interaction with the mother, including implantation, formation of a yolk-sac vascular circulation, and formation of a chorioallantoic placenta. A number of embryonic organ and body systems, including the central nervous system, gut, lungs, urogenital system and musculoskeletal system, appear to have little or no survival value in utero.

Preimplantation genetics: a case for prospective action

Preimplantation genetics describes a newly-emerging field in medical genetics, the consequence of the implementation of clinical preimplantation diagnosis and the likely future development of germ-line gene therapy. Given the existing clinical and laboratory difficulties already demonstrated in preimplantation diagnosis and the sensitive ethical issues surrounding genetic manipulation of human embryos, there is a need for 1) critical and objective evaluation of developments in this field by human and medical geneticists and 2) development of guidelines for research and clinical practice in the years ahead. We propose a course of prospective action for preimplantation genetics implemented through the newly-formed American College of Medical Genetics in order to address the ethics, safety, accuracy, cost, and overall merit of preimplantation genetics.

Genetic-based and assisted reproductive technology of the 21st century

The scientific advances of human genetics and assisted reproductive technology are redefining the concepts of health and illness by revealing the mysteries of the human genome and the process of conception, implantation, and diagnostic testing of the human embryo. The effect of these discoveries and their clinical applications will move from the tertiary to primary care arena through the ability to readily screen, diagnose, and treat some disorders and offer cure as the end result for others. In addition, the ethical, legal, and social issues, along with the attendant implications for professional practice, will need to be identified. Only a small portion of nurses have had to address the knowledge and practice issues associated with these advances. "Brave new families" are being created. Perinatal nurses must be prepared to meet the emerging needs of these families through the art and science of nursing.

National and international approaches to human germ-line gene therapy

Germ-line gene therapy, in which genetic flaws are corrected in the DNA of externally fertilized human embryos, lies in the distant yet foreseeable future. Worries about germ-line therapy have prompted international bodies to craft guidelines that are unusual for their anticipatory nature. Motivating these guidelines is the idea that a “transnational harmonization” of principles should be reached before national policies are developed. This article reviews selected national policies and international recommendations, and it concludes that national policies should be precedents for, rather than descendants of, international normative codes. The inclination to develop morally-based codes, which is implicit in transnational harmonization, will be more useful if grounded in empirically-based medical technologies and politically-tested policies rather than on abstract principles developed well in advance of technological feasibility.