Fibroblast growth factor 21 is an endocrine factor, secreted mainly by the liver, that exerts metabolic actions that favour glucose metabolism. Its role in the heart is unknown. Here we show that ...Fgf21(-/-) mice exhibit an increased relative heart weight and develop enhanced signs of dilatation and cardiac dysfunction in response to isoproterenol infusion, indicating eccentric hypertrophy development. In addition, Fgf21(-/-) mice exhibit enhanced induction of cardiac hypertrophy markers and pro-inflammatory pathways and show greater repression of fatty acid oxidation. Most of these alterations are already present in Fgf21(-/-) neonates, and treatment with fibroblast growth factor 21 reverses them in vivo and in cultured cardiomyocytes. Moreover, fibroblast growth factor 21 is expressed in the heart and is released by cardiomyocytes. Fibroblast growth factor 21 released by cardiomyocytes protects cardiac cells against hypertrophic insults. Therefore, the heart appears to be a target of systemic, and possibly locally generated, fibroblast growth factor 21, which exerts a protective action against cardiac hypertrophy.
Human cytomegalovirus (CMV) is the leading cause of congenital infection, with morbidity and mortality at birth and sequelae. Each year approximately 1–7% (Rev Med Virol 2010; 20: 311) of pregnant ...women acquire a primary CMV infection. Of these, about 30–40% transmit infection to their fetuses. The risk of serious fetal injury is greatest when maternal infection develops in the first trimester or early in the second trimester. Between 10 and 15% of congenitally infected infants are acutely symptomatic at birth and most of the survivors have serious long-term complications. Until a few years ago, laboratory testing was not possible to precisely define the maternal immune status, the recent development of advanced serological tests (IgG avidity test, IgM immunoblot and neutralizing antibody testing) allow us to identify, among pregnant women with suspected CMV, those with primary infection who are therefore at high risk of transmitting CMV to the fetus. This is done with the use of a screening test. As most maternal infections are asymptomatic, the only way to disclose primary infection is to implement specific serological testing as early in pregnancy as possible (before week 12–16 of gestation). Given the high risk of mother–fetus transmission and fetal damage, prenatal diagnosis is recommended to women with primary CMV infection contracted in the first half of pregnancy and in case of fetal abnormalities suggestive of infection. The correct interpretation of serological and virological tests followed by appropriate counselling by an expert physician is an effective tool to reduce the number of unnecessary pregnancy terminations by over 70% (Am J Obstet Gynecol 2007; 196: 221.e1).
Background
Over the last months, during the COVID‐19 pandemic, a growing number of chilblain‐like lesions were reported mainly in children and rarely in young adults. The relationship with SARS‐CoV‐2 ...infection was postulated, often without any laboratory, instrumental or clinical confirmation. The disclosure of information about chilblain‐like lesions as a COVID‐19 manifestation in social media has created concern in children’s families and paediatricians.
Objectives
To verify whether the chilblain‐like lesions were caused by SARS‐CoV‐2 infection.
Methods
Prospective study on a case series including children who presented with acral lesions at the Pediatric Dermatology Outpatient and Pediatric Emergency Unit of the University of Bologna, from 1 April to 30 April 2020. We reported demographical, laboratory and clinical features, history of close contact with COVID‐19 patients, presence of similar skin lesions in other family members, precipitating and risk factors for chilblain onset.
Results
We evaluated eight patients (five females, three males) aged between 11 and 15 years. We excluded acute or previous SARS‐CoV‐2 infection with RT‐PCR nasopharyngeal swab, serum antibody levels using chemiluminescent immunoassays. Other acute infections causing purpuric lesions at the extremities were negative in all patients. Skin lesion biopsy for histological and immunohistochemical evaluation was made in two cases and was consistent with chilblain. PCR assay on skin lesion biopsy for parvovirus B19, Mycoplasma pneumoniae and SARS‐CoV‐2 was performed in a patient and resulted negative. We identified common precipitating and risk factors: physical (cold and wet extremities, low BMI), cold and wet indoor and outdoor environment, behaviours, habits and lifestyle. We therefore reached a diagnosis of primary chilblains.
Conclusions
During the COVID‐19 pandemic, a ‘cluster’ of primary chilblains developed in predisposed subjects, mainly teenagers, due to cold exposure in the lockdown period. Laboratory findings support our hypothesis, although it is also possible that an unknown infectious trigger may have contributed to the pathogenesis.
Cytomegalovirus (CMV) is the most prevalent infectious agent causing neurological dysfunction in the developing brain. This study analysed the different patterns of tissue damage, particularly in the ...brain, of fetuses with documented CMV infection. We studied 45 fetuses at 20-21 weeks of gestation with congenital CMV infection documented by invasive positive prenatal diagnosis. At the time of amniocentesis, abnormal ultrasound findings had been recorded for 13 of the 45 fetuses (29%). Histological and immunohistochemical characterization was performed on the placenta, brain, heart, lung, liver, kidney, and pancreas. The different degrees of brain damage were correlated with tissue viral load, inflammatory response, placental functionality, and extramedullary haematopoiesis. Even though a high CMV load was detected in all amniotic fluids, brain infection occurred in only 62% of the fetuses and with different degrees of severity. Tissues with a low viral load showed a globally weak inflammatory response, and fetuses had only mild brain damage, whereas tissues with a high CMV load showed prominent infiltration of the activated cytotoxic CD8+ T-lymphocytes responsible for immune-mediated damage. Furthermore, severe placental infection was associated with diffuse villitis and necrosis, consistent with functional impairment and possible consequent hypoxic cerebral damage. Brain injury induced by CMV congenital infection may be the result of uncontrolled viral replication, immune-mediated damage by cytotoxic CD8+ T-lymphocytes, and, in the presence of placental insufficiency, fetal hypoxia.
•Novel topology optimization method for the synthesis of nanophotonic energy concentrators governed by Maxwell’s system.•Rigorous derivation of the topological derivative associated to the ...energy-density functional in electromagnetic devices.•The proposed shape functional can be defined both outside or overlapping the design (moving) domain itself.•The topological derivative-based black/white design approach conforms to practical fabrication constraints for nanodevices.•Capability in selectively producing hot-spots within the nanodevices, avoiding any issues from eigenmode calculations.
In this work, a novel topology optimization method for the synthesis of nanophotonic energy concentrators is proposed. The forward problem is governed by the Maxwell equations in the frequency domain. The basic idea consists in finding the best two phase material distribution that concentrates the energy in a given target domain. More precisely, a shape functional measuring the electrical energy of the system within a small region of the nanodevice is maximized with respect to silicon and glass spatial distribution by using the topological derivative method. Therefore, since the resulting optimization method is based on a scattering problem formulation, any issues that would come from eigenmode calculations are here avoided. In addition, the proposed shape functional can be properly defined both outside or overlapping the design (moving) domain itself, increasing the range of applications of the proposed approach. The associated topological gradient is rigorously derived and used to devise a simple and efficient black/white binary topology design algorithm, which naturally conforms to practical fabrication constraints for nanodevices. Finally, a set of numerical experiments are presented showing different features of the proposed approach, including its capability in selectively producing the required hot-spots within the nanodevices.
High-order dispersion mapping of an optical fiber Gil-Molina, A; Castañeda, J A; Londono-Giraldo, D F ...
Optics express,
2020-Feb-03, 2020-02-03, 20200203, Letnik:
28, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We report on measurements of high-order dispersion maps of an optical fiber, showing how the ratio between the third and fourth-order dispersion (β
/β
) and the zero-dispersion wavelength (λ
) vary ...along the length of the fiber. Our method is based on Four-Wave Mixing between short pulses derived from an incoherent pump and a weak laser. We find that the variations in the ratio β
/β
are correlated to those in λ
. We present also numerical calculations to illustrate the limits on the spatial resolution of the method. Due to the good accuracy in measuring λ
and β
/β
(10
% and 5% relative error, respectively), and its simplicity, the method can be used to identify fiber segments of good uniformity, suitable to build nonlinear optical devices such as parametric amplifiers and frequency comb generators.
The understanding of how bending modifies the dispersion of optical fibers, in particular, the zero-dispersion wavelength (λ
), is essential in the development of compact nonlinear optical devices ...such as parametric amplifiers, wavelength converters, soliton lasers and frequency comb generators. Typically, substantial variations in the parametric gain and/or conversion efficiency are significant for changes in λ
of ~0.1 nm, which occur for variations on the bending radius (Rb) of 1 cm or less. Measuring λ
as a function of bending radius (Rb) is challenging, as it requires detecting changes < 0.1 nm and in short fibers. By using a method based on four-wave mixing (FWM) generated by an incoherent-pump with relatively broad spectrum and a weak laser, we report measurements of λ
as a function of Rb in a dispersion-shifted fiber with <0.1 nm accuracy on λ
. This method is sensitive enough to measure small variations in λ
of ~0.04 nm in very short fibers (~20 m). We observe that λ
increases by 12 nm when Rb is decreased from 10 cm to 1 cm, and a change of 1 nm is obtained for Rb = 3 cm. We also present numerical simulations of the bent fiber that are in good agreement with our measurements, and help us to explain the observations and to predict how high-order dispersion is modified with bending. This study can provide insights for dispersion engineering, in which bending could be used as a tuning, equalization, or tailoring mechanism for λ
, which can be used in the development of compact nonlinear optical devices based on fibers or other bent-waveguide structures.
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