164 research outputs found
Non-systemic transmission of tick-borne diseases: a network approach
Tick-Borne diseases can be transmitted via non-systemic (NS) transmission.
This occurs when tick gets the infection by co-feeding with infected ticks on
the same host resulting in a direct pathogen transmission between the vectors,
without infecting the host. This transmission is peculiar, as it does not
require any systemic infection of the host. The NS transmission is the main
efficient transmission for the persistence of the Tick-Borne Encephalitis virus
in nature. By describing the heterogeneous ticks aggregation on hosts through a
\hyphenation{dynamical} bipartite graphs representation, we are able to
mathematically define the NS transmission and to depict the epidemiological
conditions for the pathogen persistence. Despite the fact that the underlying
network is largely fragmented, analytical and computational results show that
the larger is the variability of the aggregation, and the easier is for the
pathogen to persist in the population.Comment: 15 pages, 4 figures, to be published in Communications in Nonlinear
Science and Numerical Simulatio
Interplay of network dynamics and ties heterogeneity on spreading dynamics
The structure of a network dramatically affects the spreading phenomena
unfolding upon it. The contact distribution of the nodes has long been
recognized as the key ingredient in influencing the outbreak events. However,
limited knowledge is currently available on the role of the weight of the edges
on the persistence of a pathogen. At the same time, recent works showed a
strong influence of temporal network dynamics on disease spreading. In this
work we provide an analytical understanding, corroborated by numerical
simulations, about the conditions for infected stable state in weighted
networks. In particular, we reveal the role of heterogeneity of edge weights
and of the dynamic assignment of weights on the ties in the network in driving
the spread of the epidemic. In this context we show that when weights are
dynamically assigned to ties in the network an heterogeneous distribution is
able to hamper the diffusion of the disease, contrary to what happens when
weights are fixed in time.Comment: 10 pages, 10 figure
Semaphorin 4D regulates gonadotropin hormoneâreleasing hormone-1 neuronal migration through PlexinB1âMet complex
In mammals, reproduction is dependent on specific neurons secreting the neuropeptide gonadotropin hormoneâreleasing hormone-1 (GnRH-1). These cells originate during embryonic development in the olfactory placode and migrate into the forebrain, where they become integral members of the hypothalamicâpituitaryâgonadal axis. This migratory process is regulated by a wide range of guidance cues, which allow GnRH-1 cells to travel over long distances to reach their appropriate destinations. The Semaphorin4D (Sema4D) receptor, PlexinB1, is highly expressed in the developing olfactory placode, but its function in this context is still unknown. Here, we demonstrate that PlexinB1-deficient mice exhibit a migratory defect of GnRH-1 neurons, resulting in reduction of this cell population in the adult brain. Moreover, Sema4D promotes directional migration in GnRH-1 cells by coupling PlexinB1 with activation of the Met tyrosine kinase (hepatocyte growth factor receptor). This work identifies a function for PlexinB1 during brain development and provides evidence that Sema4D controls migration of GnRH-1 neurons
Characterization of the human GnRH neuron developmental transcriptome using a GNRH1-TdTomato reporter line in human pluripotent stem cells
Gonadotropin-releasing hormone (GnRH) neurons provide a fundamental signal for the onset of puberty and subsequent reproductive functions by secretion of gonadotropin-releasing hormone. Their disrupted development or function leads to congenital hypogonadotropic hypogonadism (CHH). To model the development of human GnRH neurons, we generated a stable GNRH1-TdTomato reporter cell line in human pluripotent stem cells (hPSCs) using CRISPR-Cas9 genome editing. RNA-sequencing of the reporter clone, differentiated into GnRH neurons by dual SMAD inhibition and FGF8 treatment, revealed 6461 differentially expressed genes between progenitors and GnRH neurons. Expression of the transcription factor ISL1, one of the top 50 most upregulated genes in the TdTomato-expressing GnRH neurons, was confirmed in 10.5 gestational week-old human fetal GnRH neurons. Among the differentially expressed genes, we detected 15 genes that are implicated in CHH and several genes that are implicated in human puberty timing. Finally, FGF8 treatment in the neuronal progenitor pool led to upregulation of 37 genes expressed both in progenitors and in TdTomato-expressing GnRH neurons, which suggests upstream regulation of these genes by FGF8 signaling during GnRH neuron differentiation. These results illustrate how hPSC-derived human GnRH neuron transcriptomic analysis can be utilized to dissect signaling pathways and gene regulatory networks involved in human GnRH neuron development.This article has an associated First Person interview with the first author of the paper.Peer reviewe
Circulating antimullerian hormone and steroid hormone levels remain high in pregnant women with polycystic ovary syndrome at term
Objective: To investigate plasma antimullerian hormone (AMH) concentration and its relation to steroid hormone levels in pregnant women with polycystic ovary syndrome (PCOS) and controls at term. Design: Case-control study. Setting: University-affiliated hospital. Patient(s): A total of 74 pregnant women at term: 25 women with PCOS (aged 31.6 +/- 3.9 years [mean +/- standard deviation], body mass index 24.0 +/- 3.9 kg/m2, mean gestational length 279 +/- 9 days) and 49 controls (aged 31.7 +/- 3.3 years, body mass index 24.0 +/- 3.3 kg/m2, mean gestational length 281 +/- 9 days). Intervention(s): None. Main Outcome Measure(s): Plasma AMH and steroid hormone levels. Result(s): Antimullerian hormone, T, and androstenedione levels were higher in women with PCOS at term compared with controls, whereas estrogen and P levels were similar. The differences were pronounced in women carrying a female fetus. Testosterone and AMH levels correlated positively in both groups, but E2 levels only in women with PCOS. Conclusion(s): Pregnant women with PCOS present with elevated AMH and androgen levels even at term, suggesting a hormonal imbalance during PCOS pregnancy. Differences were detected especially in pregnancies with a female fetus, raising the question of whether female pregnancies are more susceptible to AMH and steroid hormone actions. (C) Copyright (C) 2018 The Authors. Published by Elsevier Inc. on behalf of the American Society for Reproductive Medicine. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer reviewe
RelSifter: Scoring Triples from Type-like Relations - The Samphire Triple Scorer at WSDM Cup 2017
We present RelSifter, a supervised learning approach to the problem of
assigning relevance scores to triples expressing type-like relations such as
'profession' and 'nationality.' To provide additional contextual information
about individuals and relations we supplement the data provided as part of the
WSDM 2017 Triple Score contest with Wikidata and DBpedia, two large-scale
knowledge graphs (KG). Our hypothesis is that any type relation, i.e., a
specific profession like 'actor' or 'scientist,' can be described by the set of
typical "activities" of people known to have that type relation. For example,
actors are known to star in movies, and scientists are known for their academic
affiliations. In a KG, this information is to be found on a properly defined
subset of the second-degree neighbors of the type relation. This form of local
information can be used as part of a learning algorithm to predict relevance
scores for new, unseen triples. When scoring 'profession' and 'nationality'
triples our experiments based on this approach result in an accuracy equal to
73% and 78%, respectively. These performance metrics are roughly equivalent or
only slightly below the state of the art prior to the present contest. This
suggests that our approach can be effective for evaluating facts, despite the
skewness in the number of facts per individual mined from KGs.Comment: Triple Scorer at WSDM Cup 2017, see arXiv:1712.0808
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