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PubMed1979

Experimental design for the surgical relocation of the ovary into the vaginal fornix.

After translocation into the vaginal vault while attached to a pedicle consisting of the infundibulo-pelvic ligament, the ovary was found to maintain its function in laboratory primates. In the majority of the baboons the ovulatory pattern returned within a few weeks after the surgical procedure. The only significant complication was a transitory, and self-limited, infection which was evident on inspection and on the biopsy specimens, but caused no clinical symptoms. By comparing the surgical outcome in two primate species, namely Papio Cynocephalus and Macaca Arctoides, it could be deduced that the Homo Sapiens would be a more suitable experimental model than either of the laboratory primates used in this research. Because there are potentially effective methods for reducing the likelihood of postoperative infection in the relocated ovary, the experience gained by this new method suggests the possibility that it could be utilized in the future for the purpose of collecting ova for in vitro fertilization in carefully selected, and otherwise untreatable, cases of female sterility.

Animals↗
PubMed2000

Axis-inducing activities and cell fates of the zebrafish organizer.

We have investigated axis-inducing activities and cellular fates of the zebrafish organizer using a new method of transplantation that allows the transfer of both deep and superficial organizer tissues. Previous studies have demonstrated that the zebrafish embryonic shield possesses classically defined dorsal organizer activity. When we remove the morphologically defined embryonic shield, embryos recover and are completely normal by 24 hours post-fertilization. We find that removal of the morphological shield does not remove all goosecoid- and floating head-expressing cells, suggesting that the morphological shield does not comprise the entire organizer region. Complete removal of the embryonic shield and adjacent marginal tissue, however, leads to a loss of both prechordal plate and notochord. In addition, these embryos are cyclopean, show a significant loss of floor plate and primary motorneurons and display disrupted somite patterning. Motivated by apparent discrepancies in the literature we sought to test the axis-inducing activity of the embryonic shield. A previous study suggested that the shield is capable of only partial axis induction, specifically being unable to induce the most anterior neural tissues. Contrary to this study, we find shields can induce complete secondary axes when transplanted into host ventral germ-ring. In induced secondary axes donor tissue contributes to notochord, prechordal plate and floor plate. When explanted shields are divided into deep and superficial fragments and separately transplanted we find that deep tissue is able to induce the formation of ectopic axes with heads but lacking posterior tissues. We conclude that the deep tissue included in our transplants is important for proper head formation.

Animals↗
PubMedDate not supplied

The effects of the sequencing of marriage and first birth during adolescence.

Whether or not they marry, black adolescent mothers are more likely than whites to attend school following the birth of their first child. Marrying to legitimate a birth reduces the likelihood that a teenager will return to school after childbearing; this impact of marriage is much stronger among black than among white teenagers. The timing of marriage appears to affect school enrollment among white teenagers through its impact on living arrangements. However, the negative impact of marriage on educational achievement does not seem to be a consequence of earlier differences in educational expectations among the teenagers. Teenage mothers appear less likely to separate from their husbands in later years if they marry before the birth than if they marry afterward. Delaying marriage until after the birth has a long-term effect on the probability of separation among white teenage mothers, but has only a short-term impact among blacks. Among teenagers who marry before giving birth, there is little difference in the likelihood of separation between those who marry before becoming pregnant and those who do so afterward. In addition, the effect of the sequence of marriage and first birth among white teenage mothers may have declined in recent years. Adolescent mothers who do not marry before their first birth experience a longer interval between that birth and their second than do those who marry either before or during the pregnancy. These differences are primarily the result of short-term variations in the amount of time they spend married; that is, women who are unmarried when they give birth are less likely to have a second birth soon afterward.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Can premature luteinization in superovulation protocols be prevented by aspiration of an ill-timed leading follicle?

In 12 patients stimulated for in vitro fertilization and embryo transfer (IVF-ET), a single leading follicle developed, whereas the other follicles were 6 mm smaller. In 7 patients chosen at random (group A), the leading follicle was aspirated, whereas in the other 5 the leading follicle was allowed to continue growing (group B). Comparison of the hormonal pattern of both groups showed that a premature luteinizing hormone (LH) surge was avoided only in group A, and only in this group a second follicle aspiration for IVF-ET was done, and two pregnancies were achieved. In group B, aspiration for IVF-ET was canceled because of premature LH surge. It is suggested that aspiration of a single leading follicle during ovulation induction may be an efficient method to avoid premature LH surge enabling other follicles to develop up to the preovulatory stage.

Adult↗
PubMed2002

A relationship between seed development, Arabinogalactan-proteins (AGPs) and the AGP mediated promotion of somatic embryogenesis.

Arabinogalactan-protein (AGP) epitopes are known to display developmentally regulated patterns of expression in several plant tissues. Therefore, AGPs have been suggested to play a role in plant development. Somatic embryogenesis is regulated by AGPs as well as by EP3 endochitinases. Using four different methods we have analysed the composition of AGPs in immature carrot seeds. The results obtained show that: (1) the native electrophoretic mobility of such AGPs changes during development; (2) AGP epitopes in immature seeds are developmentally regulated; (3) enzymatically released fragments of AGPs show that the composition of these molecules changes as a function of development; and (4) the biological activity of AGPs on the formation of somatic embryos changes depending on the age of the seeds. Our results suggest that degradation of maternally derived AGPs occurs after fertilization, while cellularization of the endosperm leads to synthesis of a new set of AGPs. The presence of an endochitinase cleavage site as well as the capacity to increase somatic embryogenesis only occurred in AGPs that were isolated from seeds in which the endosperm had been cellularized. Apparently, both EP3 endochitinases and somatic embryogenesis-promoting AGPs are developmentally regulated in immature carrot seeds.

Journal Article↗
PubMed1983

Interconversion of structural and contractile actin gels by insertion of myosin during assembly.

Extracts of the soluble cytoplasmic proteins of the sea urchin egg form gels of different composition and properties depending on the temperature used to induce actin polymerization. At temperatures that inactivate myosin, a gel composed of actin, fascin, and a 220,000-mol-wt protein is formed. Fascin binds actin into highly organized units with a characteristic banding pattern, and these actin-fascin units are the structural core of the sea urchin microvilli formed after fertilization and of the urchin coelomocyte filopods. Under milder conditions a more complex myosin-containing gel is formed, which contracts to a small fraction of its original volume within an hour after formation. What has been called "structural" gel can be assembled by combining actin, fascin, and the 220,000-mol-wt protein in 50-100 mM KCl; the aim of the experiments reported here was to determine whether myosin could be included during assembly, thereby interconverting structural and contractile gel. This approach is limited by the aggregation of sea urchin myosin at the low salt concentrations utilized in gel assembly. A method has been devised for the sequential combination of these components under controlled KCl and ATP concentrations that allows the formation of a gel containing dispersed myosin at a final concentration of 60-100 mM KCl. These gels are stable at low (approximately 10 micron) ATP concentrations, but contract to a small volume in the presence of higher (approximately 100 micron) ATP. Contraction can be controlled by forming a stable gel at low ATP and then overlaying it with a solution containing sufficient ATP to induce contraction. This system may provide a useful model for the study of the interrelations between cytoplasmic structure and motility.

Actins↗
PubMed1980

Child spacing and child mortality among Nigerian Igbos.

Until recently, a birth interval of at least two years was the norm in the Nigerian Igbo culture, a practice necessary for infant health and survival. A study of antenatal patients of the University of Nigeria Teaching Hospital, Enugu, Nigeria, shows that this cultural pattern has been disrupted by Westernization, urbanization and consumerism. The patients studied had an average of four pregnancies in five years. Roughly half of those conceived did not survive: 41% of the patients reported having lost at least one child. Modern family planning methods are urged as replacements for the abandoned traditional methods of child spacing.

Adolescent↗
PubMed1993

Ca(2+)-related changes in the capacitation state of human spermatozoa assessed by a chlortetracycline fluorescence assay.

Chlortetracycline (CTC) fluorescence patterns were used to assess Ca(2+)-related changes in the capacitation state of human spermatozoa incubated under conditions that would affect their intracellular Ca2+ levels. Initial experiments were designed to identify consistently occurring patterns and to correlate these with acrosomal status. Incubation for up to 1 h with the ionophore A23187 (10 mumol l-1), known to promote capacitation and acrosomal exocytosis, allowed the identification of three different CTC staining patterns which were very similar to those described for mouse spermatozoa. For this reason, they were given the same nomenclature: 'F'-characteristic of uncapacitated, acrosome-intact cells; 'B'-characteristic of capacitated, acrosome-intact cells; and 'AR'-characteristic of capacitated, acrosome-reacted cells. The distribution of the three patterns in the ionophore-treated suspensions was very different from that in control suspensions treated with dimethylsulfoxide only, with a significantly higher proportion of cells displaying the B and AR patterns and a significantly lower number of cells displaying the F pattern in the ionophore-treated group at all times. A strong concordance was found between the acrosomal status of cells determined using both CTC and fluorescein-conjugated Pisum sativum agglutinin (PSA) staining methods on the same cells. Verification of PSA staining patterns with acrosomal status was obtained by means of transmission electron microscopy. The proportion of cells with uniform fluorescence in the acrosomal region correlated with acrosome-intact cells; those with only equatorial segment staining correlated with fully-reacted cells, and those exhibiting equatorial fluorescence and patchy fluorescence over the rest of the acrosomal region correlated with cells in intermediate stages of exocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcimycin↗
PubMed1990

The social impact of AIDS in Sub-Saharan Africa.

The potential expansion of the HIV epidemic and its cultural impact in sub-Saharan Africa are vast. Projections under conservative assumptions suggest that the toll of AIDS will reach five million annual deaths by 2010, although the net African population will continue to increase significantly. Cultural practices, including large differences in age between men and women at marriage and a long period of postpartum abstinence, have contributed to the frequency of extramarital relations and eased the spread of sexually transmitted diseases. In response to the spread of AIDS, social adaptations will include profound changes in sexual behavior, marriage customs, and childbearing.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Triple colour fluorescent in-situ hybridization for chromosomes X,Y and 1 on spare human embryos.

The potential for implantation of human embryos obtained by in-vitro fertilization is presumably determined to a large extent by their chromosomal constitution but cytogenetic analysis of preimplantation embryos has been hampered by a number of practical and technical problems. With the advent of fluorescent in-situ hybridization (FISH) a practical method for numerical chromosomal analysis has become available. A limited amount of data has been obtained with FISH on human embryos using probes binding to chromosomes X, Y, 16, 18 and 13/21 combined or for chromosomes X and Y or 1 and 17. It was our purpose to extend these data by the combined analysis of chromosomes X, Y and 1 in spare human embryos. A short fluorescent in-situ hybridization procedure involving the simultaneous use of three deoxyribonucleic acid probes detected with red, green, and a mixture of red and green was used to determine chromosomal abnormalities in 116 spare embryos with a poor morphological score and/or displaying one or more multinucleated blastomeres. The majority of the embryos was obtained by intracytoplasmic sperm injection. Less than half of the embryos (n = 54) were diploid and only 39 of them were uniformly XY11 or XX11; two embryos showed a non-disjunction and 13 embryos were aneuploid. Of the remainder, 22 were mosaic, nine were either haploid, triploid or tetraploid and 12 embryos were classified as chaotic. The latter pattern was particularly frequent in multinucleated blastomeres. Our data are comparable with those obtained with FISH using other chromosomal probes and confirm that the majority of preimplantation embryos carry a numerical chromosomal defect. Aneuploidy for chromosome 1 does not appear to be more common in preimplantation embryos than is reported for other chromosomes. Although the high incidence of chromosomal anomalies is presumably biased by the fact that only embryos with a poor morphological score were analysed, it nevertheless indicates that natural selection is the foremost reason for the low implantation rates of human preimplantation embryos in in-vitro fertilization (IVF) programmes.

Chromosome Aberrations↗
PubMed1989

Effect of Norplant contraceptive use on hemoglobin, packed cell volume and menstrual bleeding patterns.

A study was conducted to evaluate the effect of NORPLANT use on hemoglobin levels (HB), packed cell volume (PCV) and menstrual bleeding patterns. NORPLANT insertions were performed on 50 healthy volunteers in Ilorin, Nigeria, between January-March 1986. Whole blood samples were collected at admission, 6-month and 12-month follow-up visits, and each acceptor was asked to keep a daily bleeding calendar. Mean age of the acceptors was 32.8 years with a mean parity of 5.3 live births. Almost 50% of the acceptors indicated that they did not want any more children. After 12 month's follow-up, there were a total of three discontinuations, two for excessive menstrual bleeding and one due to husband's objection. Mean HB and PCV values remained relatively unchanged from admission to 12 months. Nearly 50% of the women experienced at least one episode of 8 or more days of continuous bleeding during the first six months of use, and about 20% reported amenorrhea of 90 or more days. Despite the incidence of menstrual bleeding irregularities, acceptability of the NORPLANT method was high as indicated by a 1-year continuation rate of 93.7 per 100 users. Clinically more important was the finding that despite a high proportion of women reporting menstrual pattern changes, HB and PCV levels remained unchanged.

Adult↗
PubMed2000

Growth patterns of breastfed infants in seven countries.

An international effort is underway to develop a new international growth reference for assessing the growth of young children, especially breastfed infants who appear to falter relative to the currently recommended National Center for Health Statistics/World Health Organization reference. While limited data from high socioeconomic status children from different parts of the world suggest that their growth patterns are similar, there is no comprehensive study of breastfed infants. The WHO Multinational Study of Breastfeeding and Lactational Amenorrhea provides bi-weekly weights and 2-4 weekly length measurements on breastfed babies from selected sites in Australia, Chile, China, Guatemala, India, Nigeria and Sweden. Multi-level modelling was used to analyse between-site differences in the growth of approximately 120 infants per site, after adjustment for maternal stature and infant feeding pattern. All mothers were literate and mean educational levels were well above national averages, but the study was not restricted to infants of high socioeconomic status. Maternal education was significantly associated with infant weight only in India. The growth curves of infants from most sites were strikingly similar, but relative to the Australians (the reference category), the Chinese babies were about 3% shorter at 12 mo of age and the Indians up to 15% lighter. The present results suggest that breastfed babies from reasonably well-off families in different continents show very similar growth patterns. However, it is important that the growth of children from South and East Asian populations be rigorously assessed in the process of developing the new international growth reference. This paper discusses the relative importance of environmental versus genetic influences in the growth of young children and illustrates the complexities involved in the analysis of growth data.

Adult↗
PubMed1991

Assessment of the late proliferative phase endometrium by ultrasonography in patients undergoing in-vitro fertilization and embryo transfer (IVF/ET).

This study reports on 330 women aged 29 to 45 years, who underwent 411 cycles of in-vitro fertilization and embryo transfer (IVF/ET). Vaginal sonograms were performed during the late proliferative phase of natural cycles and cycles of controlled ovarian hyperstimulation (COH) with gonadotrophins, to evaluate both the thickness and echogenicity of the endometrium. Findings classified as Grade I; characterized by homogeneous echogenicity of the endometrium, and Grade II; characterized by an outer peripheral layer of dense echogenicity surrounding a central sonolucent area (i.e. a 'halo pattern'). Grades I and II were subclassified on the basis of thickness into A (greater than or equal to 9 mm) and B (less than 9 mm). Grade IIA ('optimal') was associated with a clinical pregnancy rate per embryo transfer of 33% while Grades IA, IB and IIB ('poor') were associated with a rate of only 7%. Women aged 41-45 years experienced a 25% incidence of 'poor' sonographic grades while the incidence in women less than or equal to 40 years of age was 5%. The presence of various uterine pathologies was associated with 'poor' endometrial grades in 86% of cases while only 11% of normal uteri manifested 'poor' grades. 'Optimal' endometrial grades in natural cycles were consistently associated with 'optimal' grades in ensuing cycles of COH (96%). Women with 'poor' endometrial grades in natural cycles improved in 55% of cases during subsequent COH. The results of this study indicate that sonographic assessment of the endometrial lining in the late proliferative phase during both natural and COH cycles is a valuable method for screening and managing IVF/ET candidates.

Adult↗
PubMedDate not supplied

Natural fertility in northeastern Mexico.

BACKGROUND: The aims of this study were as follows: 1) to describe the fertility of a sample of Mexican women (> or =45 years of age, married, not using any family planning methods, and residing in the Mexican state of Nuevo León); 2) to determine whether or not the distribution of completed family size fits the negative binomial distribution, as in other populations studied in the world, and 3) to assess the association between fertility and 10 explanatory variables. METHODS: A sample of 410 women was interviewed at and selected from seven medical units of the Instituto Mexicano del Seguro Social (IMSS). The women were grouped by their year of birth (1896-1925 and 1926-1955) and birthplace [persons whose four grandparents were born in northeastern Mexico (NE) and outside northeastern Mexico (Not-NE)]. A binomial negative distribution analysis was assessed. Multiple linear regression was used to assess association between fertility (transformed by the use of inverse hyperbolic sines) and 10 explanatory variables, including age at marriage, heterozygosity, individual admixture, wife's education, husband's education, wife's occupation, husband's occupation, and couple's residence zone, birth year, and birthplace. RESULTS: Completed fertility was only associated with age at marriage. This population showed a fertility pattern similar to those described in Venezuelan and Brazilian populations in 1950 and 1940, respectively. CONCLUSIONS: We conclude that before worldwide family planning programs, fertility was determined mainly by natural selection forces.

Adolescent↗
PubMed1996

Effect on an aqueous extract of selenium-enriched garlic on in vitro markers and in vivo efficacy in cancer prevention.

Previous work has shown that the efficacy of cancer prevention by selenium-enriched garlic (Se-garlic) is primarily dependent on the action of selenium. An aqueous extract containing 43 micro Se/ml was prepared from lyophilized Se-garlic powder by the Soxhlet method. The activity of this Se-garlic extract was evaluated in a transformed mammary epithelial cell culture model for its effect on cell morphology, cell growth, cell cycle progression and the induction of single and double stranded breaks in DNA. Comparisons were also made with a similarly prepared extract from regular garlic, Se-methylselenocysteine (a major water-soluble seleno-amino acid identified in Se-garlic) and selenite (used for fertilizing Se-garlic). In contrast to the regular garlic extract which produced little or no modulation of the above parameters, treatment with the Se-garlic extract resulted in growth inhibition, GI phase cell cycle arrest and apoptotic DNA double strand breaks in the absence of DNA single strand breaks. This pattern of cellular responses was duplicated with exposure to Se-methylselenocysteine. Selenite, on the other hand, induced cell cycle blockage in the S/G2-M phase, and a marked increase in DNA single strand breaks (a measure of genotoxicity) in addition to growth suppression. The chemopreventive efficacy of the two garlic extracts was also investigated in the rat methylnitrosourea mammary tumor model. Both extracts were supplemented in the diet for 1 month immediately following carcinogen administration. Significant cancer protection was observed with treatment by the Se-garlic extract (at 3 p.p.m. Se in the diet), while little benefit was noted with treatment by the regular garlic extract. Based on the above in vitro and in vivo findings, it is hypothesized that the Se-garlic extract, in part via the action of Se-methylselenocysteine, is able to inhibit tumorigenesis by suppressing the proliferation and reducing the survival of the early transformed cells. Furthermore, the data also support the concept that the modulation of certain in vitro markers may be of value in predicting the effectiveness of novel forms of selenium for cancer prevention.

Animals↗
PubMed2025

The chicken chorioallantoic membrane model for human surgeries and implants.

The fertilized chick egg, particularly its chorioallantoic membrane (CAM), has emerged as a valuable model in biomedical research due to its extensive applications in vascular studies, cancer investigations, surgical advancements including neurological, gynecological, urological, and retinal procedures, drug evaluation, and implant assessments. This review provides an in-depth examination of the chicken genome, structural composition of CAM, developmental progression, vascularization patterns, and cellular regulatory mechanisms. Furthermore, it underscores the CAM's significance in assessing therapeutic kinetics, biocompatibility, biodistribution, and drug effectiveness. A particular focus is placed on its role in analyzing vascular-disrupting agents (VDAs) for cancer treatment, alongside the incorporation of advanced imaging technologies such as photodynamic therapy, radiotherapy, positron emission tomography (PET)/computed tomography (CT) imaging, ultrasound techniques, and AI-driven detection methods for real-time vascular monitoring. By evaluating its advantages, limitations, and applications, this study establishes that CAM is a crucial alternative model for biomedical research, facilitating enhanced experimental design and methodological refinement.

angiogenesis↗
PubMed2002

Survey of radiation oncologists: practice patterns of the management of stage I seminoma of testis in Canada and a selected group in the United States.

OBJECTIVE: To evaluate practice patterns of the management of stage I seminoma of testis in Canada and a selected group in the United States. MATERIALS AND METHODS: Survey among radiation oncologists treating genitourinary (GU) tumors in Canada and the RTOG GU committee members in the United States between January and March 2001. RESULTS: Response rate was 78% (73/93) in Canada and 67% (24/36) in the United States. Eighty-four percent described their clinical practice as a university affiliated teaching center, and 16% as community-based or private practice. Sixty-two percent, 31% and 7% would manage 1-5, 6-10 and > oe = 11 cases per year respectively. Almost all would perform chest x-ray (99%) and CT scan of abdomen and pelvis (100%) as staging investigation following radical inguinal orchiectomy. Forty percent also arranged CT scan of chest, while only 18% routinely obtained lymphangiogram. Seventy-eight percent offered surveillance as a management option and estimated that 20% (median) of patients would choose surveillance in their practice. Among four management options: (1. surveillance, 2. radiotherapy (RT) to the para-aortic region, 3. RT to the para-aortic and ipsilateral pelvis ('dog-leg'), 4. single-agent chemotherapy), the order of first preference was option 1 (44%), 2 (42%), and 3 (14%) for patients who wish to preserve fertility. When fertility was not a major concern, it was option 2 (43%), 3 (39%), and 1 (17%). The commonest dose-fractionation schedule was 25 Gy/20 fractions (68%). Others included 25 Gy/15 f (15%), and 25.5 Gy/17 f (4%). Forty-five percent chose the para-aortic region, while 53% used the 'dog-leg' as RT volume. Twenty-nine percent reduced RT volume from the 'dog-leg' to the para-aortic region as the result of MRC Phase III study published in 1999. CONCLUSION: There are significant variations in the practice pattern of the management of stage I seminoma of testis among radiation oncologists in Canada and a selected group in the United States.

Canada↗