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Results for “Reproductive Period”

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PubMed2000

Premarital fertility in rural South Africa: a challenge to existing population policy.

The age pattern of fertility in a rural area of South Africa under demographic surveillance (Agincourt subdistrict) was investigated over the 1992-97 period. The total fertility rate (TFR) averaged 3.3 births per woman of reproductive age over the period, a major drop from earlier estimates in the same area (6.0 births in 1970-74). Age-specific fertility rates showed an atypical bimodal pattern. They were decomposed into two components of similar magnitude: premarital fertility (among women aged 12-26) and marital fertility (among women aged 15-49). The decomposition revealed the two underlying modes: a mode of premarital fertility (among women aged 18-20) and a mode of marital fertility (among women aged 28-30). Premarital fertility accounted for 21 percent of all births and for 47 percent of births among women aged 12-26. This pattern of high premarital fertility appears to reflect a low incidence of contraceptive use before the first birth, especially among adolescents, a low prevalence of abortion, and a high contraceptive prevalence thereafter. This finding calls for a reorientation of the family planning policy, which until now has targeted married women and women who have been pregnant once, but has failed to address the contraceptive needs of young women before their first pregnancy, especially adolescents.

Adolescent↗

PubMed1986

Low rate of population increase of the Gidra Papuans in the past: a genealogical-demographic analysis.

The population increase rate of the Gidra in lowland Papua in the past was estimated using the rate of intergenerational replacement of females based on genealogical records involving 889 women, alive or deceased, who completed reproduction. During the period from a century ago to the time of manifest influence of civilization several decades ago, the Gidra had a constant annual increase rate of about 0.2%. The discussion includes a historical assessment of this rate with reference to the local conditions and an ecological explanation for its microenvironmental variation and suggests a reassessment of the methodology for studying fertility and population growth in anthropological and prehistoric populations.

Female↗

PubMed1976

Sex reversal in a freshwater sponge.

Spongilla lacustris exhibits a type of alternative hermaphroditism, new to the phylum, in which a sponge may be exclusively male or female during the period of sexual reproduction one year and the opposite sex the next year. This form of sexuality may facilitate larva production and thus dispersal following colonization of a new habitat. Gametogenesis occurs shortly after gemmule hatching in both males and females but slightly later in males.

Animals↗

PubMed1999

Developmental toxicity study of vegetable oil-derived stanol fatty acid esters.

In a standard developmental toxicity study, a mixture of vegetable oil-derived stanol fatty acid esters was administered in the diet to groups of 28 mated female HsdCpb:WU Wistar rats at concentrations that provided 0, 1, 2.5, and 5% total stanols (equivalent to 0, 1.75, 4.38, and 8.76% plant stanol esters). Test diets were adjusted with rapeseed oil to maintain an equivalent caloric content of fatty acids at each of the treatment levels. The treatment period extended from day 0 to 21 of gestation. No compound-related toxicity or clinical effects were seen in any of the treated groups. No statistically significant differences were seen in body weights or body weight gain in the low- or mid-dose groups, although slight but statistically significant decreases in mean body weight relative to controls were seen at gestation days 7 and 14 in the high-dose group. The decreases in body weight in the high-dose group may be attributable to the virtual lack of absorption of the dietary stanols. Body weight gains were equivalent to controls throughout the study except for a statistically significant decrease seen only in the 0- to 7-day gestation period in the high-dose group. No significant effects were seen on food consumption in terms of g/rat/day, but a slight, statistically significant increase was seen in the mid-dose group during gestation days 7-14. A significant increase was seen in the high-dose group during the 7- to 21-day period of gestation. Reproductive performance was not affected by the treatment. There were no statistically significant differences in uterine weight, placental weight, fetal weight, number of fetuses, number of implantation sites, number of corpora lutea, and early/late resorptions between the treated and control groups. In addition, there was no biologically meaningful effect on fetal sex ratio. Visceral and skeletal examinations did not show any significant increases in the incidence of malformations, anomalies, or variations that were considered to be treatment related. Dietary plant (8.76% plant stanol esters) stanol esters at concentrations up to 5% total stanols were concluded to have no adverse effects on reproduction or development.

Animals↗

PubMed2000

Invasion of Gleditsia triacanthos in Lithraea ternifolia Montane Forests of Central Argentina.

/ The aim of this work is to study the invasion system constituted by the alien species Gleditsia triacanthos and the native dominant Lithraea ternifolia in montane forests of central Argentina, considering life history and demographic traits of both the alien and the native species and different site conditions for population growth (good and bad sites). Matrix models are applied to project the consequences of differences in vital rates for population growth. Analyzing these models helps identify which life cycle transitions contributed most to population growth. Obtained population growth rates are considered to assess predicted rates of spread using the reaction-diffusion (R-D) model. G. triacanthos presents many of the life history traits that confer plants high potential for invasiveness: fast growth, clonal and sexual reproduction, short juvenile period, high seed production, and high seed germinability. These traits would ensure G. triacanthos invasive success and the displacement of the slow-growing, relatively less fecund native L. ternifolia. However, since disturbance and environmental heterogeneity complicate the invasibility pattern of G. triacanthos in these montane forests, the outcome of the invasion process is not straightforward as could be if only life history traits were considered.Great variation in demographic parameters was observed between populations of each species at good and bad sites. Though both good and bad sites signified increasing or at least stable populations for G. triacanthos, for L. ternifolia bad sites represented local extinction. Analyzing the results of matrices models helps design the optimal management for the conservation of L. ternifolia populations while preventing the invasion by G. triacanthos. The predicted asymptotic rate of spread for G. triacanthos at the good site was fourfold greater than the predicted one for L. ternifolia, although the difference was much smaller considering the bad site. The usefulness of the R-D model to study this invasion system is discussed.

Journal Article↗

PubMed1999

Dynamics of Puumala hantavirus infection in naturally infected bank voles (Clethrinomys glareolus).

Specific features of hantavirus infection in bank vole (Clethrionomys glareolus) were studied in the endemic area of hemorrhagic fever with renal syndrome (HFRS) in the foothills of the Ural mountains, using long-term observations on living animals by the capture-mark-recapture (CMR) method. The results demonstrated that the infection naturally circulating in the voles is chronic (lasting for up to 15 months) and asymptomatic, with a peak of Puumala virus accumulation and release from the organism during the first month after infection. It was shown that the bank vole population includes young animals with maternal immunity, which remain resistant to the Puumala virus infection for 3-3.5 months. The infection rate in voles depended on the age and sexual maturity of animals. The greatest proportion of seropositive animals was observed among overwintered males. Seroconversion in voles was more frequent during the period of high reproductive activity.

Aging↗

PubMed1993

Lymphocyte subsets in the mammary gland of sows.

The presence and localisation of lymphocyte subsets together with class II bearing cells in the mammary gland of sows, were studied at different periods of the reproductive cycle by immunohistochemistry and compared with blood. All cell types involved in the immune response were present in the mammary gland at the different stages of gestation and lactation and nearer the alveolar epithelium as gestation proceeded: T lymphocytes, including CD4+ and CD8+, B lymphocytes and class II bearing cells (epithelial cells and macrophages). The results indicated an early accumulation of T lymphocytes, specifically T helper cells, during pregnancy; the specific increase of IgA lymphocytes occurring after this phase could suggest a role for these T cells in the induction of IgA response. The local accumulation of immune cells sustains the view that the mammary gland is able to mount a true local immune response and the increase in CD8+ cells near the epithelium suggests a role in local immune defence.

Animals↗

PubMed1991

Piriformis muscle syndrome: an underdiagnosed cause of sciatica.

This is a retrospective review of 26 patients with sciatica due to the piriformis muscle syndrome. Most patients had pain in the buttock area and sciatica, and most experienced difficulty walking and sitting, even for short periods of time. Reproduction of the sciatica upon deep palpation, either by gluteal or rectal route, was diagnostic. Reproduction of sciatica occurred in 92% of the patients upon deep digital palpation and in 100% of the patients upon rectal or pelvic examination. Other signs were helpful but not consistent. After the appropriate diagnosis, the treatment was relatively easy and rewarding. This study emphasizes that the diagnosis of piriformis muscle syndrome is clinical; without the appropriate clinical examination, it can be easily misdiagnosed.

Adult↗

PubMed2004

Seasonal variations of the beta-endorphin neuronal system in the mediobasal hypothalamus of the jerboa (Jaculus orientalis).

The distribution of neurons expressing beta-endorphin immunoreactivity was explored in the brain of adult jerboa during two distinct periods characterizing its reproductive cycle. A large presence of cell bodies displaying beta-endorphin immunoreactivity occured within different parts of the mediobasal hypothalamus along its rostrocaudal extent, from the retrochiasmatic area to the posterior arcuate nucleus. Quantitatively, the highest density of immunoreactive beta-endorphin neurons was noted at the medial level of the arcuate nucleus. Furthermore, a seasonal study showed that the number of IR-beta-endorphin neurons was highest in the anterior portion of the arcuate nucleus of jerboas sacrificed in autumn as compared to those sacrificed during spring-summer. Quantitatively, the number of beta-endorphin containing neurons in autumn was 200% in comparison to that found in spring-summer. These results suggest that beta-endorphin containing neuronal population especially localized in the anterior part of arcuate nucleus, exerts an inhibitory influence on the GnRH neurosecretory system in the jerboa, notably in autumn, probably via an increasing expression of its products. The results provide morphofunctional arguments in favour of inhibitory opioid control of GnRH neurons activity and hence the neuroendocrine events regulating reproduction in jerboa.

Animals↗

PubMed2005

Historical perspective: Hormonal regulation of behaviors in amphibians.

This review focuses on research into the hormonal control of behaviors in amphibians that was conducted prior to the 21st century. Most advances in this field come from studies of a limited number of species and investigations into the hormonal mechanisms that regulate reproductive behaviors in male frogs and salamanders. From this earlier research, we highlight five main generalizations or conclusions. (1) Based on studies of vocalization behaviors in anurans, testicular androgens induce developmental changes in cartilage and muscles fibers in the larynx and thereby masculinize peripheral structures that influence the properties of advertisement calls by males. (2) Gonadal steroid hormones act to enhance reproductive behaviors in adult amphibians, but causal relationships are not as well established in amphibians as in birds and mammals. Research into the relationships between testicular androgens and male behaviors, mainly using castration/steroid treatment studies, generally supports the conclusion that androgens are necessary but not sufficient to enhance male behaviors. (3) Prolactin acts synergistically with androgens and induces reproductive development, sexual behaviors, and pheromone production. This interaction between prolactin and gonadal steroids helps to explain why androgens alone sometimes fail to stimulate amphibian behaviors. (4) Vasotocin also plays an important role and enhances specific types of behaviors in amphibians (frog calling, receptivity in female frogs, amplectic clasping in newts, and non-clasping courtship behaviors). Gonadal steroids typically act to maintain behavioral responses to vasotocin. Vasotocin modulates behavioral responses, at least in part, by acting within the brain on sensory pathways that detect sexual stimuli and on motor pathways that control behavioral responses. (5) Corticosterone acts as a potent and rapid suppressor of reproductive behaviors during periods of acute stress. These rapid stress-induced changes in behaviors use non-genomic mechanisms and membrane-associated corticosterone receptors.

Amphibians↗

PubMed1994

Correlation of semen variables and pregnancy rates for donor insemination: a 15-year retrospective.

OBJECTIVE: To determine the validity of the criteria currently used to select fertile sperm donors. DESIGN: Retrospective study of the outcome of donor insemination treatment cycles over a 15-year period. SETTING: The Reproductive Medicine Clinic of Prince Henry's Institute of Medical Research (formerly Medical Research Centre, Prince Henry's Hospital, South Melbourne, Victoria, Australia). PATIENTS: Couples (1,299) presented with severe male factor infertility (azoospermia or severe oligozoospermia) and were treated by donor insemination (10,796 treatment cycles) using cryopreserved semen from 292 normal healthy men aged between 18 and 46 years as sperm donors. MAIN OUTCOME MEASURES: Semen characteristics, including volume, count, motility, motility index, normal morphology, live cells, and post-thaw motility, were analyzed by logistic regression analysis to determine which groups of factors were related independently and significantly to pregnancy rates. RESULTS: The pregnancy rate for donor insemination was 8.9% per cycle. By logistic regression count, normal morphology, post-thaw motility (%), and post-thaw motility index together explained 28% of the variance of the pregnancy rates. Other factors, including prethaw motility characteristics (percent motility and motility index), donor age, weight, LH, FSH, and T levels, were not significant. CONCLUSIONS: The standard parameters of sperm count, morphology, and post-thaw motility are the most important factors for the selection of highly fertile donors. As most of the variability in the pregnancy rates resulted from other undetermined factors related both to the donor and the recipient, it is suggested that the pragmatic approach of discarding donors after a reasonable number of treatment failures (20 to 50) should continue.

Cryopreservation↗

PubMed2000

Sperm chromatin damage impairs human fertility. The Danish First Pregnancy Planner Study Team.

OBJECTIVE: To examine the relationship between sperm chromatin defects, evaluated by the flow cytometric (FCM) sperm chromatin structure assay (SCSA), and the probability of a pregnancy in a menstrual cycle (fecundability). DESIGN: Follow-up study. SETTING: The Section of Toxicology and Biomedical Sciences, ENEA Casaccia, Rome, Italy, and the Department of Occupational Medicine, Aarhus University Hospital, Aarhus, Denmark. PATIENT(S): Two hundred fifteen Danish first pregnancy planners with no previous knowledge of their fertility capability. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Semen samples were collected at enrollment to measure semen volume, sperm concentration, motility, and morphology (by microscopy), as well as chromatin susceptibility to in situ, acid-induced partial denaturation by the FCM SCSA. Time to pregnancy was evaluated during a 2-year follow-up period. Demographic, medical, reproductive, occupational, and lifestyle data were collected by questionnaire. Fecundability was correlated with SCSA-derived parameters. RESULT(S): Fecundability declines as a function of the percentage of sperm with abnormal chromatin and becomes small when aberrant cells are >40%. CONCLUSION(S): Optimal sperm chromatin packaging seems necessary for full expression of the male fertility potential. The SCSA emerged as a predictor of the probability to conceive in this population-based study.

Chromatin↗

PubMed2001

Dietary self-selection and discrimination threshold in wild Anastrepha obliqua females (Diptera, Tephritidae).

Experiments were performed on adult wild Anastrepha obliqua females to (I) determine whether there is a critical period during the reproductive phase when the absence of protein in the diet impairs egg production; (II) determine whether the females are able to self-select an optimal diet; and (III) determine the discrimination threshold for protein in newly emerged females as well as in 10-day old females that had either been deprived of protein or not deprived. The results showed that protein ingestion is essential during the preovipositing phase to allow egg production, that females are self-selective and that this behavior changes with age according to the reproductive status, and that protein deprivation strongly alters the discrimination threshold for protein. Newly emerged females have discriminatory thresholds similar to protein-deprived insects.

Journal Article↗

PubMed1981

Rhodopsin-like photosensitivity of isolated chicken pineal gland.

The pineal gland of lower vertebrates such as fish, amphibians and reptiles is primarily a photoreceptor organ and its electrical activity changes in response to environmental lighting, whereas the mammalian pineal gland is a secretory organ and no longer responds to direct illumination. It is uncertain whether the avian pineal gland retains a photoreceptive capability, and also whether the gland is a photosensor involved in the photo-periodic control of reproductive systems and circadian rhythms in birds. Recently, I and other workers have shown that the circadian rhythm of serotonin N-acetyltransferase activity persisted in organ cultures of chicken pineals, indicating the presence of an endogenous circadian oscillator in the gland. Also, the observation that direct illumination of cultured chicken pineals suppressed the night-time increase of N-acetyl-transferase activity suggests that the gland contains a photoreceptor. I report here that the action spectrum of the photosensitivity of the isolated chicken pineal resembles the absorption spectrum of rhodopsin.

Animals↗

PubMed2002

Menorrhagia from a haematologist's point of view. Part II: management.

The management of menorrhagia has until recently been the domain of the gynaecologist. As haematologists, we are now addressing the issue of optimal management of menorrhagia in our patients with bleeding disorders. Addressing three life periods, the menarche, reproductive years, and postchildbearing years, this review will discuss the use of oral contraceptive agents, antifibrinolytics, non-steroidal anti-inflammatory drugs, intranasal DDAVP and the new levonorgestrel-impregnated IUD. Management of specific bleeding disorders will also be reviewed for von Willebrand disease, haemophilia A and B carriers, women with factor XI deficiency and PAI-1 deficiency.

Disease Management↗

PubMed2000

The gonadotropin-releasing hormone neurosecretory system of the jerboa (Jaculus orientalis) and its seasonal variations.

The distribution of cells expressing gonadotropin-releasing hormone (GnRH) immunoreactivity was examined in the brain of adult jerboa during two distinct periods of the reproductive cycle. During spring-summer, when the jerboa is sexually active, a high density of cell bodies and fibres immunoreactive (IR) for GnRH was observed at the level of separation of the frontal lobes, in the medial septal nucleus (MS) and in the diagonal band of Broca (DBB), in the preoptic area (POA), in the organum vasculosum laminae terminalis (OVLT), in the retrochiasmatic area and hypothalamus. In autumn, when the jerboa is sexually inactive, GnRH-immunoreactivity was less intense than during spring-summer. In the POA, we noted a 55% decrease in the number of GnRH containing cells with no change in cell numbers in the MS-DBB. Furthermore, a lower density of GnRH immunopositive axon fibres is observed in all the previously mentioned structures and the immunoreaction intensity was very weak particularly within the median eminence and OVLT. Independently of the season, the GnRH immunoreactivity within neurones and fibres was similar in jerboas living in captivity and in jerboas living in their natural biotope. The effects of photoperiod on the density of POA-GnRH and arcuate nucleus beta-endorphin-containing cells were studied in jerboas maintained in long day [(LD) 16-h light, 8-h dark] and short day [(SD) 8-h light, 16-h dark] for 8 weeks. In the POA, the GnRH-IR cell number was not significantly altered by the photoperiod. Similarly, in the mediobasal hypothalamus, the number of beta-endorphin-IR neurones was not affected by such a parameter. Consequently, the GnRH seasonal variations cannot be correlated to changes in the photoperiod alone.

Adaptation, Physiological↗

PubMed2001

Saving the gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) of the Congo Basin.

The forests of the Congo Basin in equatorial Africa are home to significant populations of gorillas and chimpanzees. However, numbers are declining owing to hunting and to alteration of their habitat. Gorillas and chimpanzees are particularly vulnerable for biological reasons: slow reproduction, prolonged developmental periods and complex social behaviour. In addition, their capacity to recover from disturbance is limited and the reinforcement of wild populations with captive-born individuals is rarely an option. Compared with the critically endangered mountain gorillas and the beleaguered chimpanzees in forest fragments in West Africa, there are some reasons for optimism about the future of the Congo Basin apes: levels of threat remain relatively low; and conservation of tropical rainforests has become a priority of the international community. At the same time, knowledge of the ecological needs of wild apes has increased and non-invasive techniques now exist to monitor population health. Sadly, no animals remain truly 'wild', as their survival depends to a greater or lesser extent on management. Protected areas and laws that forbid hunting of vulnerable species are classic tools of management, but broader landscape visions are now emerging that may allow the Congo Basin to avoid the fragile scenario of larger animals persisting only in 'island' parks.

Animals↗

PubMed2004

Endometrial calbindins are critical for embryo implantation: evidence from in vivo use of morpholino antisense oligonucleotides.

The endometrium is receptive to embryo implantation only for a short period in each reproductive cycle: development of receptivity requires alterations in endometrial gene expression. Calbindin (CaBP)-d9k and CaBP-d28k are related proteins containing EF hand motifs that have a high affinity for Ca2+. We previously demonstrated that endometrial expression of CaBP-d9k mRNA is highly regulated during implantation in the mouse. This project aimed to determine the temporal and spatial expression of both CaBP proteins during early pregnancy and to establish whether they are necessary for blastocyst implantation. CaBP-d28k protein, like CaBP-d9k, was up-regulated in the endometrial epithelium just before implantation but disappeared at implantation sites after attachment. By the judicious intrauterine injection of morpholino oligonucleotides (MO) against CaBP-d9k into WT and CaBP-d28k null mice just before implantation, we selectively eliminated one or both CaBPs from the uterine epithelium. Implantation was blocked only when both CaBP-d9k and CaBP-d28k were absent: treated WT mice and untreated CaBP-d28k null mice were fertile. Furthermore, the effect on implantation was highly dependent on the timing of injection of MO. This report examining the function of implantation-related genes in the uterus using MO demonstrates that this technique is a highly effective means to specifically target uterine proteins in vivo. This study provides evidence for an absolute requirement for CaBPs during the early phase of embryo implantation, and thus that regulation of Ca2+ availability in the uterine environment of the implanting embryo is critical for successful implantation.

Animals↗