Evaluation of vaccination strategies for SIR epidemics on random networks incorporating household structure

This paper is concerned with the analysis of vaccination strategies in a stochastic SIR (susceptible → infected → removed) model for the spread of an epidemic amongst a population of individuals with a random network of social contacts that is also partitioned into households. Under various vaccine action models, we consider both household-based vaccination schemes, in which the way in which individuals are chosen for vaccination depends on the size of the households in which they reside, and acquaintance vaccination, which targets individuals of high degree in the social network. For both types of vaccination scheme, assuming a large population with few initial infectives, we derive a threshold parameter which determines whether or not a large outbreak can occur and also the probability and fraction of the population infected by such an outbreak. The performance of these schemes is studied numerically, focusing on the influence of the household size distribution and the degree distribution of the social network. We find that acquaintance vaccination can significantly outperform the best household-based scheme if the degree distribution of the social network is heavy-tailed. For household-based schemes, when the vaccine coverage is insufficient to prevent a major outbreak and the vaccine is imperfect, we find situations in which both the probability and size of a major outbreak under the scheme which minimises the threshold parameter are \emph{larger} than in the scheme which maximises the threshold parameter

Intravital imaging reveals p53-dependent cancer cell death induced by phototherapy via calcium signaling.

One challenge in biology is signal transduction monitoring in a physiological context. Intravital imaging techniques are revolutionizing our understanding of tumor and host cell behaviors in the tumor environment. However, these deep tissue imaging techniques have not yet been adopted to investigate the second messenger calcium (Ca2+). In the present study, we established conditions that allow the in vivo detection of Ca2+ signaling in three-dimensional tumor masses in mouse models. By combining intravital imaging and a skinfold chamber technique, we determined the ability of photodynamic cancer therapy to induce an increase in intracellular Ca2+ concentrations and, consequently, an increase in cell death in a p53-dependent pathway

Effect of culture in simulated microgravity on the development of mouse embryonic testes

BACKGROUND All known organisms develop and evolve in the presence of gravitational force, and it is evident that gravity has a significant influence on organism physiology and development. Microgravity is known to affect gene expression, enzyme activity, cytoskeleton organization, mitotic proliferation and intracellular signaling. OBJECTIVES: The aim of the present study was to study some aspects of the development in vitro of mouse embryonic testes in simulated microgravity. MATERIAL AND METHODS: Testes from mouse embryos (12.5-16.5 days post coitum, d.p.c.) were cultured in simulated microgravity and standard static culture conditions. The microgravity condition was provided by a Rotary Cell Culture System (RWV) bioreactor, an apparatus designated for 3D tissue and small organ cultures. After 48 h of the culture in the RWV, testis morphology and size was evaluated. RESULTS: The first observation was that the culture in the RWV bioreactor had a beneficial effect on the testis growth and on the survival of germ cells in comparison to static 2D culture methods. Moreover, we found, that RWV culture caused disorganization the gonadal tissues, namely of the testis cords. CONCLUSIONS: The results suggest that the maintenance of testis cord could be sensitive to microgravity. We hypothesize that while the effect on testis growth is due to a better nutrient and oxygen supply, the testis cord's disorganization might depend on the microgravity conditions simulated by the bioreactor. Considering the complexity of the processes involved in the formation of the testis cords and their dynamic changes during the embryo fetal period, further studies are needed to identify the causes of such effect

Close-to-Nature Silviculture to Maintain a Relict Population of White Oak on Etna Volcano (Sicily, Italy): Preliminary Results of a Peculiar Case Study

Habitat loss is a potential long-term effect of projected climate change for Mediterranean forest ecosystems. Here, we investigated the effectiveness of a close-to-nature silvicultural practice to conserve an old-growth white oak forest patch in Sicily (Italy) and promote regeneration dynamics. The study area, although small, is distinctive for its isolation, position and environmental characteristics. We conducted a Before-After Control-Impact (BACI) study to analyse the responses of different taxonomic groups (vascular plants and birds) to silvicultural treatments (selection thinning, no thinning), and to determine whether close-to-nature silviculture practices may cause significant shifts in the investigated communities. Specifically, we assessed the responses of (1) vascular plants by means of species diversity and taxonomic distinctness indices and (2) birds in terms of diversity, abundance and forest specialisation. Preliminary results suggest that cautious close-to-nature silviculture practice could-by mimicking natural gap dynamics-contribute to maintaining old-growth forest patches and promote oak seedling emergence without short-term detrimental impacts on biodiversity. Although the monitoring has to be repeated over the long-term, the multi-taxon approach and indices incorporating information on taxonomic relationships into diversity measures were demonstrated to be valuable tools for interpreting biotic community structure and dynamics

Attenuation of induced bronchoconstriction in healthy subjects: effects of breathing depth.

The effects of breathing depth in attenuating induced bronchoconstriction were studied in 12 healthy subjects. On four separate, randomized occasions, the depth of a series of five breaths taken soon (approximately 1 min) after methacholine (MCh) inhalation was varied from spontaneous tidal volume to lung volumes terminating at approximately 80, approximately 90, and 100% of total lung capacity (TLC). Partial forced expiratory flow at 40% of control forced vital capacity (V(part)) and residual volume (RV) were measured at control and again at 2, 7, and 11 min after MCh. The decrease in V(part) and the increase in RV were significantly less when the depth of the five-breath series was progressively increased (P < 0.001), with a linear relationship. The attenuating effects of deep breaths of any amplitude were significantly greater on RV than V(part) (P < 0.01) and lasted as long as 11 min, despite a slight decrease with time when the end-inspiratory lung volume was 100% of TLC. In conclusion, in healthy subjects exposed to MCh, a series of breaths of different depth up to TLC caused a progressive and sustained attenuation of bronchoconstriction. The effects of the depth of the five-breath series were more evident on the RV than on V(part), likely due to the different mechanisms that regulate airway closure and expiratory flow limitation

Post-AGB Stars in Globular Clusters and Galactic Halos

We discuss three aspects of post-AGB (PAGB) stars in old populations. (1) HST photometry of the nucleus of the planetary nebula (PN) K 648 in the globular cluster (GC) M15 implies a mass of 0.60 Msun, in contrast to the mean masses of white dwarfs in GCs of ~0.5 Msun. This suggests that K 648 is descended from a merged binary, and we infer that single Pop II stars do not produce visible PNe. (2) Yellow PAGB stars are the visually brightest stars in old populations (Mv ~ -3.3) and are easily recognizable because of their large Balmer jumps; thus they show great promise as a Pop II standard candle. Two yellow PAGB stars in the GC NGC 5986 have the same V magnitudes to within +/-0.05 mag, supporting an expected narrow luminosity function. (3) Using CCD photometry and a u filter lying below the Balmer jump, we have detected yellow PAGB stars in the halo of M31 and in its dwarf elliptical companion NGC 205. With the Milky Way zero point, we reproduce the Cepheid distance to M31, and find that NGC 205 is ~100 kpc further away than M31. The star counts imply a yellow PAGB lifetime of about 25,000 yr, and their luminosities imply masses near 0.53 Msun.Comment: 6 pages, 2 figures. To appear in proceedings of Torun, Poland, workshop on "Post-AGB Objects (Proto-Planetary Nebulae) as a Phase of Stellar Evolution," ed. S.K. Gorn

Impact of physio-chemical spinning conditions on the mechanical properties of biomimetic spider silk fibers

Artificial spider silk has emerged as a biobased fiber that could replace some petroleum-based materials that are on the market today. Recent progress made it possible to produce the recombinant spider silk protein NT2RepCT at levels that would make the commercialization of fibers spun from this protein economically feasible. However, for most applications, the mechanical properties of the artificial silk fibers need to be improved. This could potentially be achieved by redesigning the spidroin, and/or by changing spinning conditions. Here, we show that several spinning parameters have a significant impact on the fibers’ mechanical properties by tensile testing more than 1000 fibers produced under 92 different conditions. The most important factors that contribute to increasing the tensile strength are fast reeling speeds and/or employing post-spin stretching. Stretching in combination with optimized spinning conditions results in fibers with a strength of >250 MPa, which is the highest reported value for fibers spun using natively folded recombinant spidroins that polymerize in response to shear forces and lowered pH

The ubiquitin ligase LIN41/TRIM71 targets p53 to antagonize cell death and differentiation pathways during stem cell differentiation

Rapidity and specificity are characteristic features of proteolysis mediated by the ubiquitin-proteasome system. Therefore, the UPS is ideally suited for the remodeling of the embryonic stem cell proteome during the transition from pluripotent to differentiated states and its inverse, the generation of inducible pluripotent stem cells. The Trim-NHL family member LIN41 is among the first E3 ubiquitin ligases to be linked to stem cell pluripotency and reprogramming. Initially discovered in C. elegans as a downstream target of the let-7 miRNA, LIN41 is now recognized as a critical regulator of stem cell fates as well as the timing of neurogenesis. Despite being indispensable for embryonic development and neural tube closure in mice, the underlying mechanisms for LIN41 function in these processes are poorly understood. To better understand the specific contributions of the E3 ligase activity for the stem cell functions of LIN41, we characterized global changes in ubiquitin or ubiquitin-like modifications using Lin41-inducible mouse embryonic stem cells. The tumor suppressor protein p53 was among the five most strongly affected proteins in cells undergoing neural differentiation in response to LIN41 induction. We show that LIN41 interacts with p53, controls its abundance by ubiquitination and antagonizes p53-dependent pro-apoptotic and pro-differentiation responses. In vivo, the lack of LIN41 is associated with upregulation of Grhl3 and widespread caspase-3 activation, two downstream effectors of p53 with essential roles in neural tube closure. As Lin41-deficient mice display neural tube closure defects, we conclude that LIN41 is critical for the regulation of p53 functions in cell fate specification and survival during early brain development