Patient-specific probes for preimplantation genetic diagnosis of structural and numerical aberrations in interphase cells.
(9/1211)
PURPOSE: Our purpose was to evaluate the utility of translocation breakpoint-spanning DNA probes for prenatal genetic diagnosis of structural and numerical chromosome aberrations in interphase cells. METHODS: Breakpoint-spanning translocation probes were isolated from large insert DNA libraries and labeled so that the breakpoint regions were stained in different colors. Hybridization conditions were optimized using blastomeres biopsied from donated embryos. Probes were then applied to analyze patient blastomeres. RESULTS: We prepared translocation breakpoint-specific probes for 18 in vitro fertilization patients. Here, we describe the preparation of probes for two patients carrying balanced translocations involving chromosome 11 [t(11;22)(q23;q11), t(6;11)(p22.1;p15.3)]. The breakpoint cloning procedure could be accomplished in about 3-5 weeks. Additional time was needed to optimize probes. Application of probes demonstrated numerical as well as structural abnormalities. CONCLUSIONS: Breakpoint-spanning probes allow chromosome analysis in interphase cells as required for preimplantation genetic diagnosis screening of blastomeres. (+info)
Studies on the immunogenicity of protamines in humans and experimental animals by means of a micro-complement fixation test.
(10/1211)
A complement fixation study with human, monkey and rabbit sera, using purified sperm nuclear basic proteins as antigens, led to the following conclusions. (1) Protamines, the sperm-specific basic nuclear proteins, may be immunogenic in mammalians. (2) Antibodies detected in the indirect immunofluorescence test on human swollen sperm heads in sera from infertile and vasectomized men, are directed primarily against human protamines. (3) The results obtained suggested that differences in the immunization site and/or in the configuration of the immunizing protamine, may lead to the formation of antibodies directed against different antigenic determinants. Autoimmunity to protamines, following vasectomy or in infertile men, is accompanied by the formation of antibodies cross-reacting with common antigenic determinants present in protamines of other species. Induction of immunity to protamines by means of immunization with protamines-RNA complexes (in rabbits), or protamine-insulin complexes (in humans), leads to the formation of antibodies reacting more specifically with the immunizing protamine, showing only slight cross-reaction with other protamines. (4) The histone-like fraction present in mature human spermatozoa is composed mainly of histone fraction H2B. (+info)
Current status of reproductive behaviour in Africa.
(11/1211)
The current annual population growth rate of 3.2% in Africa will double the population by the year 2025. The majority of this population is below 15 years of age, and Africa concurrently also has the highest incidence of infertility in the world. Sexual behaviour, which has been poorly studied in Africa, has a direct impact on reproductive health [including fertility, infertility and sexually transmitted diseases (STDs)]. The multiple cultures and religions which characterize the African continent also affect reproductive health. Factors that have a significant effect on reproductive health in Africa include greater prevalence of extramarital/commercial sexual activity, polygamy, lower prevalence of contraceptives, reliance on traditional practices, high incidence of STDs and teenage pregnancies. High risk reproductive behaviours are predominantly displayed by adolescents, and the prevalence of STDs, including HIV (human immunodeficiency virus), is very high in this group. Pregnancy-related complications are the major cause of health-related problems in 15-19 year old girls. Maternal mortality rates in most countries remain high. Literacy rates affect these behaviours. It is apparent that changing the sexual behaviour of adolescents is one way of reversing the adverse trends, such as STD transmission, unwanted pregnancy and poor general reproductive health. (+info)
Stu-7/air-2 is a C. elegans aurora homologue essential for chromosome segregation during embryonic and post-embryonic development.
(12/1211)
We have isolated a new sterile uncoordinated C. elegans mutant, stu-7, which is defective in post-embryonic cell divisions in a regionally-specific fashion. The anterior of the worm is relatively unaffected whereas the mid-body and/or posterior are markedly thin, often resulting in worms having a central 'waist'. We have cloned stu-7 and found that it encodes a member of the recently expanding aurora sub-family of serine/threonine kinases. Elimination of maternal as well as zygotic stu-7 expression reveals that stu-7 is essential for mitosis from the first embryonic cell cycle onwards and is required for chromosome segregation though not for centrosome separation or for setting up a bipolar spindle. Multicopy expression of stu-7 also causes mitotic defects, suggesting that the level of this protein must be tightly controlled in order to maintain genetic stability during development. (+info)
Disease states associated with telomerase deficiency appear earlier in mice with short telomeres.
(13/1211)
Mice deficient for the mouse telomerase RNA (mTR-/-) and lacking telomerase activity can only be bred for approximately six generations due to decreased male and female fertility and to an increased embryonic lethality associated with a neural tube closure defect. Although late generation mTR-/- mice show defects in the hematopoietic system, they are viable to adulthood, only showing a decrease in viability in old age. To assess the contribution of genetic background to the effect of telomerase deficiency on viability, we generated mTR-/- mutants on a C57BL6 background, which showed shorter telomeres than the original mixed genetic background C57BL6/129Sv. Interestingly, these mice could be bred for only four generations and the survival of late generation mTR-/- mice decreased dramatically with age as compared with their wild-type counterparts. Fifty percent of the generation 4 mice die at only 5 months of age. This decreased viability with age in the late generation mice is coincident with telomere shortening, sterility, splenic atrophy, reduced proliferative capacity of B and T cells, abnormal hematology and atrophy of the small intestine. These results indicate that telomere shortening in mTR-/- mice leads to progressive loss of organismal viability. (+info)
Antiphospholipid antibodies in infertile couples with two consecutive miscarriages after in-vitro fertilization and embryo transfer.
(14/1211)
Of 682 women who had undergone in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) with embryo transfer, 84 were successful on two occasions, with 16 of these resulting in miscarriage before 20 completed weeks. Antiphospholipid antibodies (APA) were estimated by enzyme-linked immunosorbent assay in these women (group 1) and compared to two control groups: 42 fertile women with three or more miscarriages (group 2) and 60 women with primary infertility undergoing IVF or ICSI (group 3). An apparently higher prevalence of seropositivity was seen in group 1 women (25%) compared to the group 3 women (6.6%) and it was similar to that seen in group 2 women (21.4%). Therefore the recommendation that women with two consecutive miscarriages after IVF or ICSI should have APA estimations performed routinely may be justified. (+info)
Vitamin E: function and metabolism.
(15/1211)
Although vitamin E has been known as an essential nutrient for reproduction since 1922, we are far from understanding the mechanisms of its physiological functions. Vitamin E is the term for a group of tocopherols and tocotrienols, of which alpha-tocopherol has the highest biological activity. Due to the potent antioxidant properties of tocopherols, the impact of alpha-tocopherol in the prevention of chronic diseases believed to be associated with oxidative stress has often been studied, and beneficial effects have been demonstrated. Recent observations that the alpha-tocopherol transfer protein in the liver specifically sorts out RRR-alpha-tocopherol from all incoming tocopherols for incorporation into plasma lipoproteins, and that alpha-tocopherol has signaling functions in vascular smooth muscle cells that cannot be exerted by other forms of tocopherol with similar antioxidative properties, have raised interest in the roles of vitamin E beyond its antioxidative function. Also, gamma-tocopherol might have functions apart from being an antioxidant. It is a nucleophile able to trap electrophilic mutagens in lipophilic compartments and generates a metabolite that facilitates natriuresis. The metabolism of vitamin E is equally unclear. Excess alpha-tocopherol is converted into alpha-CEHC and excreted in the urine. Other tocopherols, like gamma- and delta-tocopherol, are almost quantitatively degraded and excreted in the urine as the corresponding CEHCs. All rac alpha-tocopherol compared to RRR-alpha-tocopherol is preferentially degraded to alpha-CEHC. Thus, there must be a specific, molecular role of RRR-alpha-tocopherol that is regulated by a system that sorts, distributes, and degrades the different forms of vitamin E, but has not yet been identified. In this article we try to summarize current knowledge on the function of vitamin E, with emphasis on its antioxidant vs. other properties, the preference of the organism for RRR-alpha-tocopherol, and its metabolism to CEHCs. (+info)
Effective treatment of subfertility: introducing the Cochrane Menstrual Disorders and Subfertility Group.
(16/1211)
The last two decades have seen a rapid explosion in research surrounding subfertility treatments. This ever-increasing volume of research has made it a difficult task for health professionals involved in the management of the subfertility to be able to assimilate the information easily. There is an urgent need for the findings from research to be synthesized into simple easy to read reviews that are both of a high quality and are based on the best evidence available. The Menstrual Disorders and Subfertility Group of the Cochrane Collaboration is attempting to address these issues by collecting a register of all the randomized controlled trials in the field of reproductive medicine and preparing systematic reviews on topics that will be of interest to healthcare workers and consumers. Readers are invited to participate in this process by identifying published and unpublished data and by helping in the process of preparing protocols and systematic reviews for inclusion in the Cochrane Library. (+info)