393 research outputs found
Effects of business recovery strategies on seismic risk and cost-effectiveness of structural retrofitting for business enterprises
Recent earthquakes in Italy have significantly affected productive activities, particularly in business interruption (BI) and, consequently, heavy losses for companies, highlighting the need for appropriate seismic risk assessment and management. To estimate seismic risk accurately, both direct (repair/ replacement) and indirect (BI) losses must be quantified. Companies\u2019 balance sheets can be used to estimate BI losses, which, however, are very sensitive to business recovery strategies (BRSs) devised by corporate managers after the seismic event. The aim of this study is to evaluate the effects of BRSs on seismic risk estimates and consequently on structural retrofitting cost-effectiveness. A loss model (including direct and indirect costs and BRS effects) was defined, based on a real-life case study (a biomedical packaging company that was damaged by the 2012 Italian earthquake but recovered soon after) and was used in parametric risk analyses assessing several types of company vulnerabilities and seismic hazards. In areas with low-to-moderate seismicity, seismic retrofitting of existing reinforced concrete factories may be justified or otherwise, depending on whether BRSs are considered or not
Presence of a functional (TTAGG)n telomere-telomerase system in aphids
The structure of the telomeres of four aphid species (Acyrthosiphon pisum, Megoura viciae, Myzus persicae and Rhopalosiphum padi) has been evaluated by Southern blotting and fluorescent in situ hybridization. This revealed that each chromosomal end consists of the (TTAGG)n repeat. The presence of a telomerase coding gene has been successively verified in the A. pisum genome, revealing that aphid telomerase presents a sequence identity ranging from 12 to 18% with the invertebrate and vertebrate homologues and possesses the two main domains involved in telomerase activity. Interestingly, telomerase expression has been verified in different somatic tissues suggesting that in aphids the telomerase activity could be not restricted as in human cells. The study of telomeres in a M. persicae strain with variable chromosome number evidenced that aphid telomerase can initiate the de novo synthesis of telomere sequences at internal breakpoints resulting in the stabilization of the chromosomal fragments
Stability domains of actin genes and genomic evolution
In eukaryotic genes the protein coding sequence is split into several
fragments, the exons, separated by non-coding DNA stretches, the introns.
Prokaryotes do not have introns in their genome. We report the calculations of
stability domains of actin genes for various organisms in the animal, plant and
fungi kingdoms. Actin genes have been chosen because they have been highly
conserved during evolution. In these genes all introns were removed so as to
mimic ancient genes at the time of the early eukaryotic development, i.e.
before introns insertion. Common stability boundaries are found in evolutionary
distant organisms, which implies that these boundaries date from the early
origin of eukaryotes. In general boundaries correspond with introns positions
of vertebrates and other animals actins, but not much for plants and fungi. The
sharpest boundary is found in a locus where fungi, algae and animals have
introns in positions separated by one nucleotide only, which identifies a
hot-spot for insertion. These results suggest that some introns may have been
incorporated into the genomes through a thermodynamic driven mechanism, in
agreement with previous observations on human genes. They also suggest a
different mechanism for introns insertion in plants and animals.Comment: 9 Pages, 7 figures. Phys. Rev. E in pres
X-linked heterochromatin distribution in the holocentric chromosomes of the green apple aphid Aphis pomi
Chromatin organization in the holocentric chromosomes of the green apple aphid Aphis pomi has been investigated at a cytological level after C-banding, NOR, Giemsa, fluorochrome staining and fluorescent in situ hybridization (FISH). C-banding technique showed that heterochromatic bands are exclusively located on X chromosomes. This data represents a peculiar feature that clearly contradicts the equilocal distribution of heterochromatin typical of monocentric chromosomes. Moreover, silver staining and FISH carried out with a 28S rDNA probe localized rDNA genes on one telomere of each X chromosome; CMA(3) staining reveals that these silver positive telomeres are, the only GC-rich regions among A. pomi heterochromatin, whereas all other C-positive bands are DAPI positive thus containing AT-rich DNA
Does vitamin D play a role in autoimmune endocrine disorders? A proof of concept
In the last few years, more attention has been given to the "non-calcemic" effect of vitamin D. Several observational studies and meta-analyses demonstrated an association between circulating levels of vitamin D and outcome of many common diseases, including endocrine diseases, chronic diseases, cancer progression, and autoimmune diseases. In particular, cells of the immune system (B cells, T cells, and antigen presenting cells), due to the expression of 1α-hydroxylase (CYP27B1), are able to synthesize the active metabolite of vitamin D, which shows immunomodulatory properties. Moreover, the expression of the vitamin D receptor (VDR) in these cells suggests a local action of vitamin D in the immune response. These findings are supported by the correlation between the polymorphisms of the VDR or the CYP27B1 gene and the pathogenesis of several autoimmune diseases. Currently, the optimal plasma 25-hydroxyvitamin D concentration that is necessary to prevent or treat autoimmune diseases is still under debate. However, experimental studies in humans have suggested beneficial effects of vitamin D supplementation in reducing the severity of disease activity. In this review, we summarize the evidence regarding the role of vitamin D in the pathogenesis of autoimmune endocrine diseases, including type 1 diabetes mellitus, Addison's disease, Hashimoto's thyroiditis, Graves' disease and autoimmune polyendocrine syndromes. Furthermore, we discuss the supplementation with vitamin D to prevent or treat autoimmune diseases
Arithmetic, working memory, and visuospatial imagery abilities in children with poor geometric learning
Many children fail in geometric learning, but factors underlying these failures have not been explored in detail. The present study addresses this issue by comparing fifth and sixth-grade children who had good or poor geometric learning, and were otherwise comparable on verbal intelligence, gender and age. Results showed that children with poor geometric learning have deficits in both arithmetic and geometric problem solving but they are more impaired in the latter. Results also showed that poor geometric learners have weaknesses in working memory, calculation, and visuospatial mental imagery. The results from logistic regressions pointed out that mental imagery skills and arithmetic problem solving ability had the highest discriminatory power in distinguishing between the two groups. Theoretical and practical implications of this research for designing interventions to help poor geometric learners are discussed. © 2018 Elsevier Inc
The old and new tests for celiac disease: which is the best test combination to diagnose celiac disease in pediatric patients?
Sperm DNA integrity in relation to exposure to environmental perfluoroalkyl substances – A study of spouses of pregnant women in three geographical regions.
Perfluoroalkyl substances (PFASs) can interfere with male reproductive function, but evidence in humansis limited. Six hundred four fertilemen(199 from Greenland, 197 from Poland and 208 from Ukraine) wereenrolled in the study. We measured four PFASs in serum (PFOS, PFOA, PFNA and PFHxS) and concurrentDNA damage in spermatozoa by sperm chromatin structure assay (SCSA) and in situ terminal deoxynucleotidyltransferase dUTP nick-end labeling (TUNEL) assay, apoptotic markers in semen (Fas-receptorand Bcl-xL), and reproductive hormones in serum. No association between PFASs and SCSA, apoptoticmarkers or reproductive hormones emerged.Weobserved a slight increase in SHBG and TUNEL-positivitywith increased PFOA exposure in men from Greenland. Thus, consistent evidence that PFAS exposureinterferes with sperm DNA fragmentation, apoptosis or reproductive hormones was not found
Holocentric Chromosomes of Luzula elegans Are Characterized by a Longitudinal Centromere Groove, Chromosome Bending, and a Terminal Nucleolus Organizer Region
The structure of holocentric chromosomes was analyzed in mitotic cells of Luzula elegans. Light and scanning electron microscopy observations provided evidence for the existence of a longitudinal groove along each sister chromatid. The centromere-specific histone H3 variant, CENH3, colocalized with this groove and with microtubule attachment sites. The terminal chromosomal regions were CENH3-negative. During metaphase to anaphase transition, L. elegans chromosomes typically curved to a sickle-like shape, a process that is likely to be influenced by the pulling forces of microtubules along the holocentric axis towards the corresponding microtubule organizing regions. A single pair of 45S rDNA sites, situated distal to Arabidopsis-telomere repeats, was observed at the terminal region of one chromosome pair. We suggest that the 45S rDNA position in distal centromere-free regions could be required to ensure chromosome stability. Copyright (C) 2011 S. Karger AG, Base
Intrinsic factor recognition promotes T helper 17/T helper 1 autoimmune gastric inflammation in patients with pernicious anemia.
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