11 research outputs found
Polycystic Ovary Syndrome: A Brain Disorder Characterized by Eating Problems Originating during Puberty and Adolescence
Polycystic ovary syndrome (PCOS) is an endocrine condition associated with
reproductive and psychiatric disorders, and with obesity. Eating disorders, such as bulimia
and recurrent dieting, are also linked to PCOS. They can lead to the epigenetic dysregulation
of the hypothalamic–pituitary–gonadal (HPG) axis, thereby impacting on ovarian folliculogenesis.
We postulate that PCOS is induced by psychological distress and episodes of overeating and/or
dieting during puberty and adolescence, when body dissatisfaction and emotional distress are often
present. We propose that upregulated activation of the central HPG axis during this period can be
epigenetically altered by psychological stressors and by bulimia/recurrent dieting, which are common
during adolescence and which can lead to PCOS. This hypothesis is based on events that occur during
a largely neglected stage of female reproductive development. To date, most research into the origins
of PCOS has focused on the prenatal induction of this disorder, particularly in utero androgenization
and the role of anti-Müllerian hormone. Establishing causality in our peripubertal model requires
prospective cohort studies from infancy. Mechanistic studies should consider the role of the gut
microbiota in addition to the epigenetic regulation of (neuro) hormones. Finally, clinicians should
consider the importanc
Prorenin periconceptionally and in pregnancy: Does it have a physiological role?
Pregnancy demands major cardiovascular, renal and endocrine changes to provide an adequate blood supply for the growing fetus. The renin-angiotensin-aldosterone system plays a key role in this adaptation process. One of its components, prorenin, is released in significant amounts from the ovary and uteroplacental unit. This review describes the sources of prorenin in the periconception period and in pregnancy, including its modulation by in-vitro fertilization protocols, and discusses its potential effects, among others focusing on preeclampsia. It ends with discussing the long-term consequences, even in later life, of inappropriate renin-angiotensin-aldosterone system activity in pregnancy and offers directions for future research. Ultimately, a full understanding of the role of prorenin periconceptionally and during pregnancy will help to develop tools to diagnose and/or prevent reproductive complications
Determinants of Maternal Renin-Angiotensin-Aldosterone-System Activation in Early Pregnancy: Insights From 2 Cohorts
Context: The corpus luteum (CL) secretes prorenin, renin’s inactive precursor. It may thus contribute to
the renin-angiotensin-aldosterone-system (RAAS) activation that is required for maternal adaptation in
pregnancy. Whether this activation is disturbed in pregnancies lacking a CL is unknown.
Objective: The objective of this work is to investigate maternal RAAS determinants in early pregnancy.
Design and Setting: Two observational prospective cohort studies took place at 2 tertiary referral
hospitals.
Patients and Intervention(s): Pregnancies (n = 277) were stratified by CL number and in vitro fertilization
(IVF) protocol: 0 CL (programmed cycle frozen embryo transfer [FET], n = 28), 1 CL (natural cycle FET,
n = 41 and spontaneous conceptions, n = 139), and more than 1 CL (ovarian stimulation and fresh
embryo transfer, n = 69).
Methods: Quantification was performed for maternal prorenin, renin, and aldosterone blood levels at 5,
9, and 11 weeks of gestation.
Results: Prorenin and renin were lower in the absence of a CL at all time points when compared to 1 CL,
whereas prorenin, renin, and aldosterone were higher in the presence of more than 1 CL vs 1 CL (P < .05).
Ovarian stimulation with menopausal gonadotropin resulted in higher prorenin, renin, and aldosterone
concentrations during the late first trimester than recombinant follicle-stimulating hormone (P < .05).
Prorenin, and to a lesser degree renin, correlated positively with serum progesterone and relaxin, but not
serum estradiol. Total follicle diameter, body mass index (BMI), polycystic ovary syndrome (PCOS), and antimüllerian hormone (AMH) were additional determinants of circulating prorenin. Finally, pregnancies
conceived in the
First-trimester maternal renin-angiotensin-aldosterone system activation and the association with maternal telomere length after natural and IVF/ICSI conceived pregnancies: the Rotterdam periconception cohort
Objective To study associations between the first-trimester maternal determinants of renin-angiotensin-aldosterone system (RAAS) activation and telomere length (TL) in pregnancies conceived natural and after IVF/ICSI. Methods In 145 pregnancies of the Rotterdam Periconception cohort renin, prorenin and aldosterone concentrations were measured in maternal blood at 9 weeks gestational age (GA). TL was measured by qPCR at 20 weeks GA. Results A significantly negative correlation was found between renin and TL, which was attenuated for prorenin but not observed for aldosterone. Maternal TL was significantly shorter in pregnancies conceived after in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) compared to natural pregnancies. Conclusion The negative association between first-trimester maternal renin and maternal TL, and the shorter maternal TL in women after IVF/ICSI treatment compared to natural pregnancies, substantiates the role of excessive RAAS activation
Mikromekaaninen oskillaattori
Tässä diplomityössä tutustuttiin kapasitiivisesti kytketyllä mikromekaanisella resonaattorilla stabiloidun sähkömekaanisen oskillaattorin teoriaan: resonaattorin mekaniikkaan ja vahvistimen elektroniikkaan.
Esitetyn teorian pohjalta suunniteltiin ja rakennettiin sähkömekaaninen 500 kHz:n Pierce-oskillaattori.
Prototyypin toiminta demonstroitiin mittauksin.
Prototyypin mittauksissa todennettiin mikromekaanisen oskillaattorin värähtelytaajuuden ja -amplitudin riippuvuus resonaattorin biasjännitteestä; mittaustulokset olivat ennusteiden mukaiset.
Oskillaattorin värähtelytarkkuutta kuvaava vaihekohina mitattiin tarkoitukseen suunnitellulla laitteistolla.
Mitattu vaihekohina oli -123dBc@SkHz.
Prototyypissä käytettiin palkkiresonaattoria, jonka epälineaarisuuden seurauksena oskillaattorin ulostulo oli säröytynyt.
Työssä pohdittiin myös fysikaalisia rajoja palkkiresonaattoriin perustuvan mikromekaanisen oskillaattorin suorituskyvylle