641 research outputs found

    Many-body approach to proton emission and the role of spectroscopic factors

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    The process of proton emission from nuclei is studied by utilizing the two-potential approach of Gurvitz and Kalbermann in the context of the full many-body problem. A time-dependent approach is used for calculating the decay width. Starting from an initial many-body quasi-stationary state, we employ the Feshbach projection operator approach and reduce the formalism to an effective one-body problem. We show that the decay width can be expressed in terms of a one-body matrix element multiplied by a normalization factor. We demonstrate that the traditional interpretation of this normalization as the square root of a spectroscopic factor is only valid for one particular choice of projection operator. This causes no problem for the calculation of the decay width in a consistent microscopic approach, but it leads to ambiguities in the interpretation of experimental results. In particular, spectroscopic factors extracted from a comparison of the measured decay width with a calculated single-particle width may be affected.Comment: 17 pages, Revte

    An antagonism between Spinophilin and Syd-1 operates upstream of memory-promoting presynaptic long-term plasticity

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    We still face fundamental gaps in understanding how molecular plastic changes of synapses intersect with circuit operation to define behavioral states. Here, we show that an antagonism between two conserved regulatory proteins, Spinophilin (Spn) and Syd-1, controls presynaptic long-term plasticity and the maintenance of olfactory memories in Drosophila. While Spn mutants could not trigger nanoscopic active zone remodeling under homeostatic challenge and failed to stably potentiate neurotransmitter release, concomitant reduction of Syd-1 rescued all these deficits. The Spn/Syd-1 antagonism converged on active zone close F-actin, and genetic or acute pharmacological depolymerization of F-actin rescued the Spn deficits by allowing access to synaptic vesicle release sites. Within the intrinsic mushroom body neurons, the Spn/Syd-1 antagonism specifically controlled olfactory memory stabilization but not initial learning. Thus, this evolutionarily conserved protein complex controls behaviorally relevant presynaptic long-term plasticity, also observed in the mammalian brain but still enigmatic concerning its molecular mechanisms and behavioral relevance

    High aldosterone-to-renin variants of CYP11B2 and pregnancy outcome

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    Background. Increased aldosterone concentrations and volume expansion of normal pregnancies are hallmarks of normal pregnancies and blunted in pre-eclampsia. Accordingly, we hypothesized an active mineralocorticoid system to protect from pre-eclampsia. Methods. In pregnant women (normotensive n = 44; pre-eclamptic n = 48), blood pressure, urinary tetrahydro-aldosterone excretion and activating polymorphisms (SF-1 site and intron 2) of the aldosterone synthase gene (CYP11B2) were determined; 185 non-pregnant normotensive individuals served as control. Amino acid-changing polymorphisms of the DNA- and agonist-binding regions of the mineralocorticoid receptor were evaluated by RT-PCR, SSCP and sequencing. Results. Urinary tetrahydro-aldosterone excretion was reduced in pre-eclampsia as compared to normal pregnancy (P < 0.05). It inversely correlated with blood pressure (r = 0.99, P < 0.04). Homozygosity for activating CYP11B2 polymorphisms was preferably present in normotensive as compared to pre-eclamptic pregnancies, identified (intron 2, P = 0.005; SF-1 site, P = 0.016). Two mutant haplotypes decreased the risk of developing pre-eclampsia (RR 0.16; CI 0.05-0.54; P < 0.001). In contrast, intron 2 wild type predisposed to pre-eclampsia (P < 0.0015). No functional mineralocorticoid receptor mutant has been observed. Conclusions. High aldosterone availability is associated with lower maternal blood pressure. In line with this observation, gain-of-function variants of the CYP11B2 reduce the risk of developing pre-eclampsia. Mutants of the mineralocorticoid receptor cannot explain the frequent syndrome of pre-eclampsi

    CRISPR-induced double-strand breaks trigger recombination between homologous chromosome arms

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    CRISPR–Cas9–based genome editing has transformed the life sciences, enabling virtually unlimited genetic manipulation of genomes: The RNA-guided Cas9 endonuclease cuts DNA at a specific target sequence and the resulting double-strand breaks are mended by one of the intrinsic cellular repair pathways. Imprecise double-strand repair will introduce random mutations such as indels or point mutations, whereas precise editing will restore or specifically edit the locus as mandated by an endogenous or exogenously provided template. Recent studies indicate that CRISPR-induced DNA cuts may also result in the exchange of genetic information between homologous chromosome arms. However, conclusive data of such recombination events in higher eukaryotes are lacking. Here, we show that in Drosophila, the detected Cas9-mediated editing events frequently resulted in germline-transmitted exchange of chromosome arms—often without indels. These findings demonstrate the feasibility of using the system for generating recombinants and also highlight an unforeseen risk of using CRISPR-Cas9 for therapeutic intervention

    Placental expression of the angiogenic placental growth factor is stimulated by both aldosterone and simulated starvation

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    Aldosterone is an important factor supporting placental growth and fetal development. Recently, expression of placental growth factor (PlGF) has been observed in response to aldosterone exposure in different models of atherosclerosis. Thus, we hypothesized that aldosterone up-regulates growth-adaptive angiogenesis in pregnancy, via increased placental PlGF expression. We followed normotensive pregnant women (n = 24) throughout pregnancy and confirmed these results in a second independent first trimester cohort (n = 36). Urinary tetrahydroaldosterone was measured by gas chromatography-mass spectrometry and corrected for creatinine. Circulating PlGF concentrations were determined by ELISA. Additionally, cultured cell lines, adrenocortical H295R and choriocarcinoma BeWo cells, as well as primary human third trimester trophoblasts were tested in vitro. PlGF serum concentrations positively correlated with urinary tetrahydroaldosterone corrected for creatinine in these two independent cohorts. This observation was not due to PlGF, which did not induce aldosterone production in cultured H295R cells. On the other hand, PlGF expression was specifically enhanced by aldosterone in the presence of forskolin (p < 0.01) in trophoblasts. A pronounced stimulation of PlGF expression was observed with reduced glucose concentrations simulating starvation (p < 0.001). In conclusion, aldosterone stimulates placental PlGF production, enhancing its availability during human pregnancy, a response amplified by reduced glucose supply. Given the crucial role of PlGF in maintaining a healthy pregnancy, these data support a key role of aldosterone for a healthy pregnancy outcome

    Angiotensin receptors in GtoPdb v.2023.1

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    The actions of angiotensin II (Ang II) are mediated by AT1 and AT2 receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Angiotensin receptors [63, 155]), which have around 30% sequence similarity. The decapeptide angiotensin I, the octapeptide angiotensin II and the heptapeptide angiotensin III are endogenous ligands. losartan, candesartan, olmesartan, telmisartan, etc. are clinically used AT1 receptor blockers

    Angiotensin receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

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    The actions of angiotensin II (Ang II) are mediated by AT1 and AT2 receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Angiotensin receptors [61, 152]), which have around 30% sequence similarity. The decapeptide angiotensin I, the octapeptide angiotensin II and the heptapeptide angiotensin III are endogenous ligands. losartan, candesartan, telmisartan, etc. are clinically used AT1 receptor blockers

    THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: G protein-coupled receptors

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    The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15538. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate
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