Children’s Privilege in COVID-19: The Protective Role of the Juvenile Lung Morphometry and Ventilatory Pattern on Airborne SARS-CoV-2 Transmission to Respiratory Epithelial Barriers and Disease Severity

The incidence of severe COVID-19 in children is low, and underlying mechanisms for lower SARS-CoV-2 susceptibility and self-limiting disease severity are poorly understood. Severe clinical manifestations in adults require SARS-CoV-2 inoculation in the lower respiratory tract, establishing a pulmonary disease phase. This may be either accomplished by direct inoculation of the thoracic region upon exposure to virion-laden aerosols, or by infection of the upper respiratory system and aspiration of virion-laden aerosols originating right there into the lower respiratory tract. The particularities of epithelial barriers as the anatomical site of first viral deposition specifically determine the initial characteristics of an innate immune response, emerging respiratory tissue damage and dysfunctionality, and hence, severity of clinical symptoms. We, thus, investigated by in silico modeling whether the combined effect of juvenile lung morphometry, children’s ventilatory pattern and the peculiarities of the virion-laden aerosols’ properties, render children more resilient to aerosol deposition in the lower respiratory tract. Our study presents evidence for major age-dependent differences of the regional virion-laden aerosol deposition. We identified deposition hotspots in the alveolar–interstitial region of the young adult. Our data reveal that children are void of corresponding hotspots. The inoculum quantum in the alveolar–interstitial region hotspots is found to be considerably related to age. Our results suggest that children are intrinsically protected against SARS-CoV-2 inoculation in the lower respiratory tract, which may help to explain the lower risk of severe clinical manifestations associated with a pulmonary phase.

Morphological effects of bacterial compounds on the testes of Eupemphix nattereri (Anura)

Amphibians are susceptible to environmental pollutants and these compounds influence the development, morphology, physiology, behavior, and reproduction of these animals. Escherichia coli is common in aquatic habitats of frogs and could also damage their reproductive activity. Thus, our objective was to evaluate the effects of E. coli lipopolysaccharide on the testes of Eupemphix nattereri after 2, 6, 12, and 24 hours. As in other anurans, the testes of E. nattereri are paired structures and spermatogenesis into the locule is cystic, with mast cells in the interstitial region as well as testicular melanocytes. The administration of lipopolysaccharide decreased the absolute locular volume after 12 h while increasing the interstitial volume. In addition, lipopolysaccharide treatment decreased the absolute volume of all cell types in animals analyzed after 12 h. The amount of mast cells in the interstitial region increased after 12 h of inoculation. Acute exposure to lipopolysaccharide clearly alters testicular morphology, decreasing the volume of both locular and germ cells. However, acute treatment did not impair spermatogenesis and after 24 h, the treatment effects were minimized. Thus, this study was the first to demonstrate that lipopolysaccharide is a potential agent for causing damage to the testes of anurans.

Evolution of Thermal Donors in Silicon Enhanced by Self-Interstitials

The time dependence of thermal donor (TD) concentration, N(t), during annealing at 450oC was measured in samples cut from a single slab of silicon containing bands of grown-in microdefects of different types. An enormous impact of the microdefect type on the kinetic curve was observed. Samples from the interstitial region showed simple linear rise in N(t). The samples from an inner part of the vacancy region showed a complicated oscillating variation with an abrupt disappearance of the TDs at some moment followed by an immediate restoration of a linear rise. In samples from the marginal H-band of the vacancy region, an initial anneal does not produce TDs. However if this anneal was followed by a quench, subsequent anneals produce a linear rise in N(t). On the other hand, if the sample was slowly cooled, the subsequent production of TDs remained almost negligible. These observed peculiarities are accounted for by enhanced TD growth in the presence of self-interstitials (I) - due to IO species serving as vehicles for oxygen transport.

Role of TGF-β1 in the development of pancreatic fibrosis in Otsuka Long-Evans Tokushima Fatty rats

Recently established Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of naturally occurring obesity diabetes, exhibit progressive accumulation of connective tissue in the pancreas. The present study was designed to determine the pathogenic role of transforming growth factor-β1 (TGF-β1) in the development of pancreatic fibrosis in OLETF rats by investigating the serial changes in the expression of TGF-β1 and extracellular matrix (ECM) in the pancreas. Progressive proliferation of connective tissue arose from the interstitial region surrounding islets at 20 wk of age and extended to the exocrine pancreas adjacent to the islets. TGF-β1 mRNA levels in the pancreas increased at 20 wk of age and reached a peak value at 30 wk of age. Fibronectin (FN) and procollagen types I and III mRNAs peaked at 20 wk of age and remained at higher levels than those in the nondiabetic counterparts Long-Evans Tokushima Otsuka rats until 50 wk of age. Immunoreactivities for TGF-β1 and FN were found in islets of OLETF rats at 20 wk of age and were seen in acinar and interstitial cells at 50 wk of age. Moreover, α-smooth muscle actin was located at interstitial region surrounding the islets. Proliferation of the connective tissue in the pancreas of OLETF rats closely correlated with expression of TGF-β1 and ECM. Our results suggest that the development of pancreatic fibrosis in OLETF rats extends from endocrine to exocrine pancreas and that TGF-β1 is involved in pancreatic fibrosis of OLETF rats.

Effect of Boron and Hydrogen on the Electronic Structure of Ni3Al

Using first-principles electronic structure calculations based on the Linear-Muffin-Tin Orbital (LMTO) method, we have investigated the effects of interstitial boron and hydrogen on the electronic structure of the L12 ordered intermetallic Ni3A1. When it occupies an octahedral interstitial site entirely coordinated by six Ni atoms, we find that boron enhances the charge distribution found in the strongly-bound “pure” Ni3AI crystal: Charge is depleted at Ni and Al sites and enhanced in interstitial region. Substitution of Al atoms for two of the Ni atoms coordinating the boron, however, reduces the interstitial charge density between certain atomic planes. In contrast to boron, hydrogen appears to deplete the interstitial charge, even when fully coordinated by Ni atoms. We suggest that these results are broadly consistent with the notion of boron as a cohesion enhancer and hydrogen as an embrittler.