1,720,966 research outputs found
Modulation of atrial natriuretic peptide receptors in rat pregnancy
No full textThe mechanisms underlying the net fluid/electrolyte gain during pregnancy are not fully understood. Utilizing virgin, pregnant (7, 16 and 21 days gestation), estradiol-17beta- or progesterone-treated female rats, we have examined the role of atrial natriuretic peptide (ANP) and of its receptors in the adaptation of body fluid homeostasis during pregnancy. Pregnancy and progesterone attenuate the ANP-mediated inhibition on aldosterone production in adrenal zona, glomerulosa (ZG) cells. The ribonuclease protection assay and Western analysis revealed that ZG natriuretic peptide guanylyl cyclase-linked (GC) receptors are mainly GC-A and that they are downregulated by pregnancy. In addition, pregnancy downregulates GC-A and GC-B receptors in the uterus; however, it does not modulate GC-linked receptors in the lung. It is concluded that the downregulation of ZG GC-A receptors could lead to a decrease in the aldosterone-suppressant effects of ANP and that the decrease in uterine GC-A and GC-B receptors could lead to a decrease in the tocolytic effects of ANP during pregnancy
Atrial natriuretic factor and renal function during pregrancy in the rat
No full textUsing the rat as a model we tested the hypothesis that pregnancy might lead to an attenuation of the diuretic/natriuretic effects of atrial natriuretic factor (ANF) to allow physiologically required fluid expansion. Our studies revealed that this was indeed the case. Effects of ANF on fluid and sodium excretion as well as on glomerular filtration rate were significantly reduced during pregnancy This decrease in the renal effects of ANF during pregnancy was not associated with any changes in the pharmacokinetics or renal metabolism of ANF. However, binding studies demonstrated a significant decrease in guanylyl cyclase (GC)-linked ANF receptors and a decrease in ANF stimulated cGMP production in glomeruli and papillae of pregnant rats. The ribonuclease protection assay and Western blot analysis revealed that pregnancy caused a significant decrease in GC-A-linked ANF receptors in renal papillae. It is concluded that pregnancy is associated with attenuation of the renal effects of ANF and this is due to a downregulation of GC-A-linked ANF receptors which might reflect physiological adjustment to facilitate fluid/electrolyte expansion
Unassisted homebirths in Afghanistan: a qualitative exploration of underlying reasons
No full textUnassisted homebirths pose significant maternal health risks in Afghanistan, where nearly one-third of births occur at home without skilled birth attendants. Data from 2020 showed the maternal mortality ratio is 620 per 100,000 live births, due to pregnancy and childbirth complications. This thesis explored what factors contribute to unassisted homebirths in Afghanistan from the perspectives of Afghan women and community members. Guided by the social-ecological model, this qualitative case study examined four levels of influence: intrapersonal, interpersonal, community, and institutional. Data was collected through in-depth interviews with Afghan women who had experienced unassisted homebirths and focus group discussions with male and female community members, providing insights into the familial, cultural, and systemic factors influencing choices for birthplace and birth care.
The data indicated that most interview participants had limited knowledge of pregnancy and delivery care, partly due to their lack of access to a reliable source of health information, reinforcing a preference for unassisted homebirth. Patriarchal gender norms like women’s extensive involvement in domestic or agricultural roles, restricted mobility, and limited financial autonomy, along with family dynamics—particularly the influence of elder women, especially mothers-in-law, and male relatives—further constrained women’s ability to seek skilled birth attendance. Cultural beliefs and traditions, including a preference for family-centred childbirth at home, and concerns about modesty also contributed to this preference for unassisted homebirth. Inadequate access to skilled birth attendants—due to distance, financial barriers, lack of transportation, disrespectful care, and perception of poor-quality care—contributed to the perpetuation of unassisted homebirths
Surrogacy and commercial surrogacy in Canada: understanding the domestic landscape and Canada’s role in cross-border reproductive care
No full textSurrogacy, a practice in which a woman agrees to carry a pregnancy for another couple or
individual, raises many important questions and concerns regarding ethics, equity, and health.
This is especially true in cases of paid or commercial surrogacy. Despite non-commercial surrogacy being legal in Canada, the practice is poorly understood in part due to unclear
legislation and regulation and a lack of empirical research. The purpose of this study was to
explore the thoughts, perceptions, and attitudes Canadian reproductive health service users hold
towards surrogacy and commercial surrogacy and to investigate the role Canada may be playing
in international markets of commercial surrogacy and cross-border reproductive care. Our study
showed that Canadian reproductive health service users are overwhelmingly supportive of
surrogacy and wish it was more accessible. Support for commercial surrogacy was more limited,
in part due to the major barriers that cost and accessibility already pose to accessing assisted
reproductive health services in Canada. We also found that Canada continues to play a role in
international markets of commercial surrogacy and cross-border reproductive care, with many
Canadian reproductive health service users viewing international commercial surrogacy as a viable option to have a family.Includes bibliographical references (pages 64-68
On the occurrence and significance of estradiol-17 as a uninary conversion product of injected estrone or estradiol-17 l in the domestic fowl.
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Estrogen conjugates in hen's urine.
No full textIt is well established that estrogen activity plays major roles in the physiology of reproduction in the hen. This aspect has been covered in a number of reviews, e.g., Sturkie (1958), Lorenz (1954), Van Tienhoven (1959), Parkes and Marshall (1956). [...
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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