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Platelet-activating factor content in human spermatozoa and pregnancy outcome.

OBJECTIVE: To determine whether platelet-activating factor (PAF) content in human spermatozoa from an isolated population is related to fertilization and pregnancy outcome. DESIGN: Prospective analysis of PAF content in human spermatozoa after a Percoll gradient wash and its relation to fertilization and pregnancy outcome. SETTING: University-based reproductive genetics laboratory. SUBJECT(S): Couples undergoing assisted reproduction. INTERVENTION(S): Lipids extracted from Percoll gradient spermatozoa were quantitated for PAF content by a specific radioimmunoassay. MAIN OUTCOME MEASURE(S): The relation between spermatozoa-derived PAF levels and motility, concentration, morphology, and fertilization and pregnancy rates were determined by using regression analysis and the Student t-test. RESULT(S): Radioimmunoassay and regression analysis showed a significant and positive relation between PAF content in human spermatozoa and concentration and motility indices and implantation rate. Patients who became pregnant had a significantly higher PAF content in the spermatozoa used (7.285 pmol/10(6) cells) than did patients who did not become pregnant (2.990 pmol/10(6) cells). CONCLUSION(S): The PAF content in human spermatozoa has a significant and positive relation with motility and concentration indices and implantation rate. Pregnancy rates but not fertilization rates may be predicted by measuring PAF levels in an isolated subpopulation of human spermatozoa.

Embryo Implantation↗

The de Watteville Memorial Lecture: reproductive technologies and genetic advances in obstetrics and gynecology.

Public fascination with genetics and the new reproductive technologies seem ubiquitious. Although interest in genetic causation for diseases is not new, attention is increasing. There are several predictable reasons for this. One is the overall decrease in deaths due to infection. As a result, genetic factors producing birth defects loom relatively larger. This is also coupled with the public's increased desire for the ideal pregnancy, especially given a decreased population rate. Finally, the public's appetite is whetted by the increasing number of heritable diseases whose molecular basis is being elucidated. We shall focus on three general areas in which genetic technology increasingly impacts upon the obstetrician/gynecologist: genetics of pregnancy losses, genetics of sex determination and the common gynecologic disorders, and finally prenatal genetic diagnosis, particularly in preimplantation genetics and recovering fetal cells from maternal blood. Most of these topics are discussed in a recent text, where extensive references are available.

Abortion, Spontaneous↗

Genetic disorders affecting reproduction and periparturient care.

There are numerous genetic diseases influencing reproduction and periparturient care in dogs including such disorders as anasarca, cleft palate, swimmers, congenital heart disease, and the various conditions that cause excessive bleeding. It is probable that all breeds of dogs are at risk for these or other traits that influence whelping and neonatal care. Therefore, genetic counseling should be considered as an important aspect of prenatal and pediatric veterinary medicine.

Animals↗

Clones, controversy, and criminal law: a comment on the proposal for legislation governing assisted human reproduction.

In the past few years there has been a tremendous amount of regulatory conflict and social controversy in the area of reproductive genetics. The Canadian government has recently released a proposal for legislating in this complex arena. Although the proposed Bill contains many positive elements, it is argued that the use of the criminal law as a regulatory mechanism is neither warranted nor appropriate. The author suggests a more flexible and responsive system of moratoriums and licenses that would enable review and adjustment to the realities of emerging reproductive technologies is a better approach.

Canada↗

Reproductive, developmental, and genetic toxicology of ioversol.

The authors examined the reproductive, developmental, and genetic toxicity of ioversol in several in vivo and in vitro systems. In Segments I, II, and III reproductive toxicity studies, ioversol did not produce teratogenic effects in either rats or rabbits at daily intravenous dose levels of up to 3.2 g I/kg/day. Daily intravenous injections in male and female rats did not adversely affect fertility or reproductive function. Offspring derived from dams treated with ioversol also developed and reproduced in a normal fashion. Four genetic toxicity studies employing bacterial and mammalian assay systems, and using both in vitro and in vivo methods, indicated that ioversol did not possess mutagenic or clastogenic activity.

Abnormalities, Drug-Induced↗

Old-growth red spruce forests as reservoirs of genetic diversity and reproductive fitness.

Old-growth forests are assumed to be potential reservoirs of genetic diversity for the dominant tree species, yet there is little empirical evidence for this assumption. Our aim was to characterize the relationship of stand traits, such as age, height and stem diameter, with the genetic and reproductive status of old-growth and older second-growth stands of red spruce (Picea rubens Sarg.) in eastern Canada. We found strong relationships between height growth (a fitness trait) and measures of genetic diversity based on allozyme analyses in red spruce. The negative relationship between height and the proportion of rare alleles suggests that high proportions of these rare alleles may be deleterious to growth performance. Latent genetic potential, however, showed a significant and positive relationship with height. Stand age was not correlated to height, but was correlated to seedling progeny height. In late-successional species such as red spruce, age and size (e.g., height and stem diameter) relationships may be strongly influenced by local stand disturbance dynamics that determine availability of light, growing space, moisture and nutrients. In larger and older stands, age appeared to provide a good surrogate measure or indicator for genetic diversity and progeny height growth. However, in smaller and more isolated populations, these age and fitness relationships may be strongly influenced by the effects of inbreeding and genetic drift. Therefore, older populations or old-growth forests may represent superior seed sources, but only if they are also of sufficient size and structure (e.g., stem density and spatial family structure) to avoid the effects of inbreeding and genetic drift. Thus, larger and older forests appear to have an important evolutionary role as reservoirs of both genetic diversity and reproductive fitness. Given the rapid environmental changes anticipated (as a result of climate change, increasing population isolation through fragmentation, or following the introduction of exotic pests and diseases) these older populations of trees may have a valuable function in maintaining the adaptive potential of tree species.

Genetic Variation↗

Segregation analysis and genetic counseling when both parents carry balanced chromosomal translocations.

OBJECTIVE: To assess the risk of chromosomally abnormal offspring and discuss counseling approach when both parents carry balanced translocations. DESIGN: Theoretical segregation analysis is performed and use of empiric data is used in genetic counseling. SETTING: Patients are referred to Division of Reproductive Genetics at the University of Tennessee, Memphis. PATIENTS, PARTICIPANTS: The mother, heterozygous for reciprocal translocation 46,XX, rcp(7;13)(p21;q22) and father, heterozygous for Robertsonian translocation 45,XY,rob(13q;14q) were referred for genetic counseling concerning risks of chromosomally abnormal offspring. INTERVENTIONS: Segregation analysis, genetic counseling, and chorionic villus sampling. MAIN OUTCOME MEASURE(S): A cumulative risk was derived to use for counseling purposes. Cytogenetics using GTG-banding was performed on cultured chorionic villus cells. RESULTS: Theoretical risk of this couple having chromosomally abnormal offspring was 40.5%. On the basis of empirical data and risk factors inherent in the specific translocations, the maternal contribution at midtrimester was 3.5%; the paternal contribution was 1% to 2%. The sum of these risks was used in counseling. CONCLUSIONS: The fetus was found to be 46,XY,rcp(7;13)(p21;q22).

Abortion, Habitual↗

A genetic analysis of reproductive barriers in Phacelia dubia.

Investigations into the genetic basis of reproductive barriers among recognized and putative varieties in Phacelia dubia have provided evidence that even among closely related taxa, multiple pathways can lead to reproductive isolation. A nuclear-based reproductive barrier, expressed as partial hybrid sterility of both pollen and ovules, isolated each pair of recognized varieties. There was no evidence of pre- or post-fertilization barriers; all reproductive barriers were manifested as hybrid gametic sterility. Reproductive relationships of two putative varieties were studied to examine the early stages of reproductive isolation in this group. Both putative varieties exhibited partial reproductive isolation from the recognized varieties in spite of their lack of morphological differentiation from recognized varieties. The barrier isolating one putative variety was similar to the barrier among recognized varieties. The second putative variety and a recognized variety were partially isolated by a unidirectional, nuclear-cytoplasmic barrier that reduced only pollen fertility. The nuclear-cytoplasmic barrier suggested a new application of Haldane's rule.

Alleles↗

Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Targhee sheep.

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight, and wool traits were estimated using REML with animal models for Targhee sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station, Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated with the parameters estimated from the single-trait and bivariate analyses were compared across years of birth with respect to genetic trends. The numbers of observations were 38,625 for litter size at birth and litter size at weaning, 33,994 for birth weight, 32,715 for weaning weight, 36,807 for fleece weight and fleece grade, and 3,341 for staple length. Direct heritability estimates from single-trait analyses were 0.10 for litter size at birth, 0.07 for litter size at weaning, 0.25 for birth weight, 0.22 for weaning weight, 0.54 for fleece weight, 0.41 for fleece grade, and 0.65 for staple length. Estimate of direct genetic correlation between litter size at birth and weaning was 0.77 and between birth and weaning weights was 0.52. The estimate of genetic correlation between fleece weight and staple length was positive (0.54), but was negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.69). Estimates of genetic correlations were near zero between birth weight and litter size traits and small and positive between weaning weight and litter size traits. Fleece weight was slightly and negatively correlated with both litter size traits. Fleece grade was slightly and positively correlated with both litter size traits. Estimates of correlations between staple length and litter size at birth (-0.14) and litter size at weaning (0.05) were small. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small, whereas estimates between weight traits and staple length were positive and small. Estimated breeding values averaged by year of birth from both the single- and seven-trait analyses for the prolificacy and weight traits increased over time, whereas those for fleece weight decreased slightly and those for the other wool traits were unchanged. Estimated changes in breeding values over time did not differ substantially for the single-trait and seven-trait analyses, except for traits highly correlated with another trait that was responding to selection.

Animals↗

Genetic diagnosis in the first trimester: the norm for the 1990s.

Increasing technical capabilities and patient motivation for earlier and more private prenatal genetic diagnosis have allowed us to alter the concept of first-trimester genetic diagnosis from being rare to routine in our tertiary Reproductive Genetics Center. As public awareness of available services has increased, we have seen steadily increasing numbers and proportion of patients who are referred by their physicians earlier, who schedule tests earlier, opting to have earlier testing, and accept slightly higher risks in return for earlier results and privacy. Analysis of our clinical and laboratory results and complication rates suggests that first-trimester genetic diagnosis by either chorionic villus sampling or early amniocentesis may be offered to virtually all patients who would be candidates in the midtrimester. We believe that this trend will accelerate, making first-trimester diagnosis the norm, rather than the exception, for the 1990s.

Acetylcholinesterase↗

Genetic epidemiology and schizophrenia: a study of reproductive fitness.

Genetic epidemiological studies have demonstrated markedly reduced rates in reproduction among schizophrenic patients. According to evolutionary theory, behavioral and psychological phenotypes are selected based on ecological "fit". Where differential survival or reproductive success exists, genotype frequencies are altered in subsequent generations. In the case of schizophrenia, lower rates of reproduction constitute a negative selection factor that should reduce genes in the population associated with the expression of the disease--ultimately leading to decreases in prevalence. However, studies reveal a stable prevalence of about 1% over time. Attempts to explain the apparent contradiction between negative selection and stable prevalence have taken several forms. One explanation suggests that reproductive rates in relatives of schizophrenic patients are increased--compensating for reproductive loss in affected family members. Family data from schizophrenic patients at the Maryland Psychiatric Research Center were compared with those of healthy volunteers and volunteers with schizophrenia spectrum personality (SSP) disorders. Controlling for important socio-cultural and demographic variables, a multiple regression model revealed a significant increase in the number of siblings associated with schizophrenia. No differences in reproductive fitness were found among normal and SSP volunteers. This observed pattern in reproductive fitness provides one mechanism by which prevalence rates can remain stable despite lower reproductive rates among individuals with schizophrenia. Evidence of increased reproductive fitness in relatives suggests the need to consider the complex interactions of proximate and ultimate (evolutionary) mechanisms in the expression of schizophrenia.

Adult↗

Genetic testing and primary care: a new ethic for a new setting.

For several decades, clinical geneticists have espoused two key ethical principles, nondirectiveness and confidentiality. These principles made a great deal of sense in the highly personal and controversial setting of reproductive genetics. Now that clinical genetics has entered the primary care setting, clinicians are rethinking the strength of their commitment to these traditional norms and they are revamping their ethical priorities. Patients increasingly need advice about whether they should take genetic tests and whether and how they should respond to the test results. Patients also need to know about how this information will impact family members and whether other members of their family should be tested. Clinical geneticists may even consider breaking individual confidentiality in order to prevent harms to family members. Although clinical geneticists do not need to abandon nondirectiveness and confidentiality in this new setting, they may not strictly adhere to these principles in some circumstances in order to benefit patients and their families.

Confidentiality↗

[Professional and ethical challenges in reproductive biology and genetics at the beginning of the ne millennium].

About 15 to 20 percent of couples are infertile. Developments in reproductive biology have enabled treatment of these couples by means of assisted reproduction. In a broader sense, assisted reproductive technologies involve all methods aiming to restore impaired reproductive function. Preimplantation genetic testing, a new form of prenatal diagnosis, is a result of convergency in the development of assisted reproduction and genetics, and allows couples at risk of transferring hereditary diseases to their offspring to diagnose such abnormalities as early as immediately before or after conception. This article describes technologies of assisted reproduction and preimplantation genetic diagnosis, and discusses ethical as well as legal issues in reproductive medicine.

Bioethics↗

Genetic aetiology of reproductive failures.

The percentage of couples who have problems with reproduction is growing in industrialised nations. Clear genetic aetiology of reproductive failures can be discovered in at least one-sixth of them. All these couples should undergo a comprehensive genetic examination including karyotyping of both partners. Results were obtained over a period of 12 years (1985-97) when studying couples with reproductive failures by taking their detailed family histories and by cytogenetic analysis of their karyotypes. The study subjects were 410 couples (i.e. 820 persons) with different types of reproductive failure from Prague and its surroundings. In 3.16%, one member had an aberration of autosomes and, in 4.38%, one member had an aberration of sex chromosomes. Of these 7.3% had, besides infertility and/or repeated spontaneous abortions, the birth of a child with a polygenic congenital malformation. A detailed genetic investigation of couples with reproductive failures should not be neglected when trying to find the best treatment.

Journal Article↗

The interface between assisted reproductive technologies and genetics: technical, social, ethical and legal issues.

The interface between assisted reproductive technologies (ART) and genetics comprises several sensitive and important issues that affect infertile couples, families with severe genetic diseases, potential children, professionals in ART and genetics, health care, researchers and the society in general. Genetic causes have a considerable involvement in infertility. Genetic conditions may also be transmitted to the offspring and hence create transgenerational infertility or other serious health problems. Several studies also suggest a slightly elevated risk of birth defects in children born following ART. Preimplantation genetic diagnosis (PGD) has become widely practiced throughout the world for various medical indications, but its limits are being debated. The attitudes towards ART and PGD vary substantially within Europe. The purpose of the present paper was to outline a framework for development of guidelines to be issued jointly by European Society of Human Genetics and European Society of Human Reproduction and Embryology for the interface between genetics and ART. Technical, social, ethical and legal issues of ART and genetics will be reviewed.

Ethics, Medical↗

ESHRE preimplantation genetic diagnosis (PGD) consortium: data collection II (May 2000).

In 1997, the ESHRE PGD Consortium was formed as part of the ESHRE Special Interest Group on Reproductive Genetics, in order to undertake a long-term study of the efficacy and clinical outcome of preimplantation genetic diagnosis (PGD). In December 1999, the first PGD Consortium report was published discussing referrals of 323 couples, 392 PGD cycles and 82 pregnancies and 79 children born. In the second round of data collection, contributing centres were asked to send in data from their PGD activities before January 1997, as well as from 1st October 1998 until 1st May 2000, in order to have as complete as possible an overview of PGD practices in these centres. A further 563 referrals were sent in as well as 926 PGD cycles, and data on 89 pregnancies (including seven pregnancies ongoing from the previous group) and 83 children were collected. This has led to a considerable amount of cumulative data being acquired: over a period of 7 years (the oldest PGD cycle reported dates from 1994), referral data on 886 couples, cycle data on 1318 PGD cycles and data on 163 pregnancies and 162 babies were collected. In all, these data are encouraging: they show first, that the practice of PGD is becoming more and more established, and an increasing number of different applications is emerging; and second, that collecting these data is worthwhile, as they will be a valuable source of information for all those involved, e.g. in counselling patients and interacting with governmental bodies.

Aneuploidy↗

Genetic influences on reproduction of female red deer (Cervus elaphus) (2) seasonal and genetic effects on the superovulatory response to exogenous FSH.

This study evaluated the influences of seasons and genotype on the superovulatory response to a standardised oFSH regimen in red deer (Cervus elaphus scoticus) and its hybrids with either wapiti (C.e. nelsoni) or Père David's (PD) deer (Elaphurus davidianus). Adult red deer (n=9), F(1) hybrid wapiti x red deer (n=6), and maternal backcross hybrid PD x red deer (i.e., 14 PD hybrid; n=9) were kept together in the presence of a vasectomised stag for 13 months. At 6 weekly intervals, all hinds received a standardised treatment regimen used routinely to induce a superovulatory response in red deer hinds, with 10 consecutive treatments spanning an entire year. This involved synchronisation with intravaginal progesterone devices and delivery of multiple injections of oFSH (equivalent to 72 units NIH-FSH-S(1)). Laparoscopy to assess ovarian response was performed 6-7 days after the removal of the devices. Both season and genotype had significant effects on ovulation rate (OR) and total follicular stimulation (TFS) (P<0.05). For all the three genotypes, ovarian responses were highest from March to November (breeding season) and lowest in the period from December to January, inclusive. Mean OR for red deer hinds ranged from 3.7 to 1.8 during the breeding season, with no observable trend. All red deer hinds were anovulatory during December and January. A similar pattern occurred for 14 PD hybrids, although mean OR during the breeding seasons were twofold lower than for the red deer. For F(1) wapiti hybrids, the first two treatments in March and April resulted in the highest mean OR observed (15.6 and 11.7, respectively). Thereafter, mean values ranged between 6.3 and 4.7 for the remainder of the breeding season. Furthermore, mean OR of 3.0 and 0.5 were recorded in December and January, respectively. For the red deer and F(1) wapiti hybrids, between-hind variation in OR was not randomly distributed across the treatment dates, indicating that the individuals varied significantly in their ability to respond to oFSH, at least within a given season.In conclusion, the study has shown that relative to red deer, F(1) wapiti hybrid hinds exhibit a higher sensitivity to oFSH, whereas 14 PD hybrid hinds have a lower sensitivity. However, individual variation within genotype was very marked. A seasonal effect was apparent for all genotypes, although some F(1) wapiti hybrid hinds exhibited ovulatory responses throughout the year.

Administration, Intravaginal↗