Search results for "growth"
showing 10 items of 5134 documents
New insights into the role of spermine in Arabidopsis thaliana under long-term salt stress
2010
Polyamines (putrescine, spermidine and spermine) are traditionally implicated in the response of plants to environmental cues. Free spermine accumulation has been suggested as a particular feature of long-term salt stress, and in the model plant Arabidopsis thaliana the spermine synthase gene (AtSPMS) has been reported as inducible by abscisic acid (ABA) and acute salt stress treatments. With the aim to unravel the physiological role of free spermine during salinity, we analyzed polyamine metabolism in A. thaliana salt-hypersensitive sos mutants (salt overlay sensitive; sos1-1, sos2-1 and sos3-1), and studied the salt stress tolerance of the mutants in spermine and thermospermine synthesis …
Evaluation of the SOS/umu-test post-treatment assay for the detection of genotoxic activities of pure compounds and complex environmental mixtures.
2000
This study presents an evaluation of the SOS/umu-test after introducing an additional dilution and incubation in the post-treatment assay. This treatment reduces the influence of coloured test compounds that otherwise affect the colorimetric determination of the beta-galactosidase activity and the bacterial growth measurement during the testing of complex environmental samples. The post-treatment assay significantly increased the beta-galactosidase activity and consequently the enzyme induction ratios at higher doses of model genotoxins 4-nitroquinoline-N-oxide, N-methyl-N'-nitro-N-nitrosoguanidine, 2-aminoanthracene, benzo(a)pyrene with low or no effect on the sensitivity of the test itsel…
Effects of chitosan films on the growth of Listeria monocytogenes, Staphylococcus aureus and Salmonella spp. in laboratory media and in fish soup.
2009
The objective of this study was to assess the antimicrobial effectiveness of chitosonium acetate films on the growth of Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus. The samples were tested in both laboratory conditions using Tryptone Soy Broth (TSB) and in a real food system using fish soup. The study was carried out at different temperatures (4, 12, and 37 degrees C) in order to discern the influence of such variables. Moreover, a sensory evaluation of the final product was performed as a parameter of consumer acceptance. The results showed a significant reduction of the bacterial growth, which greatly depended on the bacteria type, the temperature of incubation and t…
Long term effect of teenage birth on earnings: Evidence from a British cohort study
2016
We use data from the 1970 British Cohort Study and evaluate the effect of teenage motherhood on hourly earnings at age 30, 34, 38, and 42 using alternative non-experimental estimation methods including linear regression, matching methods, and Heckman sample selection models. We conclude that teenage motherhood has a significant negative long-term effect on hourly wages. At age 42, teenage mothers earn 12% less than other women and 29% less than women who have not had any children. When compared to non-teenage mothers, the pay penalty reduces over time and becomes insignificant on the long term.
PHD3 regulates EGFR internalization and signalling in tumours
2014
Tumours exploit their hypoxic microenvironment to induce a more aggressive phenotype, while curtailing the growth-inhibitory effects of hypoxia through mechanisms that are poorly understood. The prolyl hydroxylase PHD3 is regulated by hypoxia and plays an important role in tumour progression. Here we identify PHD3 as a central regulator of epidermal growth factor receptor (EGFR) activity through the control of EGFR internalization to restrain tumour growth. PHD3 controls EGFR activity by acting as a scaffolding protein that associates with the endocytic adaptor Eps15 and promotes the internalization of EGFR. In consequence, loss of PHD3 in tumour cells suppresses EGFR internalization and hy…
Development of a morphogenetically active scaffold for three-dimensional growth of bone cells: biosilica-alginate hydrogel for SaOS-2 cell cultivation
2013
Polymeric silica is formed from ortho-silicate during a sol–gel formation process, while biosilica is the product of an enzymatically driven bio-polycondensation reaction. Both polymers have recently been described as a template that induces an increased expression of the genes encoding bone morphogenetic protein 2 (BMP-2) and osteoprotegerin in osteoblast-related SaOS-2 cells; simultaneously or subsequently the cells respond with enhanced hydroxyapatite formation. In order to assess whether the biocompatible polymeric silica/biosilica can serve as a morphogenetically active matrix suitable for three-dimensional (3D) cell growth, or even for 3D cell bioprinting, SaOS-2 cells were embedded i…
Heparin functionalized polyaspartamide/polyester scaffold for potential blood vessel regeneration
2013
An interesting issue in tissue engineering is the development of a biodegradable vascular graft able to substitute a blood vessel and to allow its complete regeneration. Here, we report a new scaffold potentially useful as a synthetic vascular graft, produced through the electrospinning of α,β-poly(N-2-hydroxyethyl) (2-aminoethylcarbamate)-D,L-aspartamide-graft-polylactic acid (PHEA-EDA-g-PLA) in the presence of polycaprolactone (PCL). The scaffold degradation profile has been evaluated as well as the possibility to bind heparin to electrospun fibers, being it a known anticoagulant molecule able to bind growth factors. In vitro cell compatibility has been investigated using human vascular e…
A new approach to the crystal growth of Hg1−xMnxTe by the cold travelling heater method (CTHM)
2001
Abstract In order to obtain crystals with a homogeneous composition and to reduce the Hg high pressure related to the temperature synthesis reaction between the components in elemental form, Hg 1− x Mn x Te bulk crystals were produced by the cold travelling heater method (CTHM). Following the technique initially proposed for the growth of CdHgTe by the Triboulet group, the feed material was a split ingot of two segments, one of HgTe and the other of MnTe, with cross-sectional areas chosen to establish the desired final composition. The growth was carried out at a temperature of 600°C and a rate of 2 mm/h. The Hg 1− x Mn x Te crystals have been characterised by scanning electron microscopy, …
Microstructural modifications resulting from the dehydration of gypsum
2001
Various faces of dehydrated gypsum-cleaved blocks and single crystals have been investigated using optical microscopy, SEM, and TEM. The orientation of the cracks with respect to the initial gypsum structure and the Miller indices of all possible crack planes have been determined. These crack planes have been found to be few and to correspond to planes of high atomic density in the initial and final structures, therefore characterised by a low surface tension. These observations allow us to propose cracking criteria based on general concepts of crystal growth. The cracks' dimensions measured on different faces of the pseudomorph are distributed over several orders of magnitude and seems to …
Does the Pension System’s Income Statement Really Matter? A Proposal for An NDC Scheme with Disability and Minimum Pension Benefits
2019
This paper develops a full accounting model for monitoring the solvency of a notional defined contribution (NDC) pension scheme with disability and minimum pension benefits. Using the annual report of the Swedish pension system as a benchmark (TSPS, 2019), we extend the “Swedish” actuarial balance developed by Perez-Salamero et al. (2017) by adding an income statement which fully explains the reasons behind the changes in the system’s solvency by type of benefit. In line with the reference model, assets and liabilities are measured at present value at each reporting date, and changes in present value are reported in each period as income or expenses and are included on the income statement.…