406 research outputs found
PathOrganic – Risks and Recommendations Regarding Human Pathogens in Organic Vegetable Production Chains
PathOrganic assesses risks associated with the consumption of fresh and minimally
processed vegetables due to the prevalence of bacterial human pathogens in plant
produce. The project evaluates whether organic production poses a risk on food safety,
taking into consideration sources of pathogen transmission (e.g. animal manure).
The project also explores whether organic versus conventional production practices
may reduce the risk of pathogen manifestation. In Europe, vegetable-linked outbreaks
are not well investigated. A conceptual model together with novel sampling strategies
and specifically adjusted methods provides the basis for large-scale surveys of organically
grown plant produce in five European countries. Critical control points are
determined and evaluated and factors contributing to a food safety problem are analyzed
in greenhouse and field experiments. The project aims at developing a quantitative
risk assessment model and at formulating recommendations for improving food
safety in organic vegetable production
Analytical description of quasivacuum oscillations of solar neutrinos
We propose a simple prescription to calculate the solar neutrino survival
probability P_{ee} in the quasivacuum oscillation (QVO) regime. Such
prescription is obtained by matching perturbative and exact analytical results,
which effectively take into account the density distribution in the Sun as
provided by the standard solar model. The resulting analytical recipe for the
calculation of P_{ee} is shown to reach its highest accuracy |\Delta P_{ee}| <
2.6 x 10^{-2} in the whole QVO range) when the familiar prescription of
choosing the solar density scale parameter r_0 at the
Mikheyev-Smirnov-Wolfenstein (MSW) resonance point is replaced by a new one,
namely, when r_0 is chosen at the point of ``maximal violation of
adiabaticity'' (MVA) along the neutrino trajectory in the Sun. The MVA
prescription admits a smooth transition from the QVO regime to the MSW
transition one. We discuss in detail the phase acquired by neutrinos in the
Sun, and show that it might be of relevance for the studies of relatively short
timescale variations of the fluxes of the solar \nu lines in the future
real-time solar neutrino experiments. Finally, we elucidate the role of matter
effects in the convective zone of the Sun.Comment: 25 pages (RevTeX) + 11 figures (postscript
Is astronomy possible with neutral ultra-high energy cosmic ray particles existing in the Standard Model?
The recently observed correlation between HiRes stereo cosmic ray events with
energies E ~ 10 EeV and BL Lacs occurs at an angle which strongly suggests that
the primary particles are neutral. We analyze whether this correlation, if not
a statistical fluctuation, can be explained within the Standard Model, i.e.,
assuming only known particles and interactions. We have not found a plausible
process which can account for these correlations. The mechanism which comes
closest -- the conversion of protons into neutrons in the IR background of our
Galaxy -- still under-produces the required flux of neutral particles by about
2 orders of magnitude. The situation is different at E ~ 100 EeV where the flux
of cosmic rays at Earth may contain up to a few percent of neutrons pointing
back to the extragalactic sources.Comment: 7 pages, 1 figur
Development of the Tilburg Pregnancy Distress Scale: the TPDS
Contains fulltext :
96807.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Pregnant women with high levels of stress, depression and/or anxiety are at increased risk for adverse perinatal outcomes and impaired neurologic and emotional development of the offspring. Pregnancy specific instruments to measure psychological functioning during gestation are scarce and do not define items based on in-depth interviews of pregnant and recently delivered women. The current study developed a pregnancy specific scale that measures psychological functioning using in-depth interviews. METHODS: Three focus groups were formed to discuss issues most relevant to pregnancy distress; 22 candidate items were derived for pilot testing (study I, n = 419) its psychometric properties by means of explorative factor analyses (EFA). This resulted in a 17-item TPDS which was further explored by confirmatory factor analyses (CFA) and concurrent and construct validity assessment (study II, n = 454). RESULTS: EFA in study I suggested a two component solution (negative affect (NA) and partner involvement (PI)). CFA in study II resulted in a higher order model of the NA subscale into three more subscales: NA regarding confinement, delivery and general health. TPDS, EPDS and GAD-7 were all significantly correlated. CONCLUSIONS: The TPDS constitutes a valid and user friendly instrument to assess pregnancy distress. In addition to its proven ability to pick up pregnancy specific negative affect it also includes an important sub-scale measuring perceived partner involvement
MAGE-A cancer/testis antigens inhibit MDM2 ubiquitylation function and promote increased levels of MDM4
Melanoma antigen A (MAGE-A) proteins comprise a structurally and biochemically similar sub-family of Cancer/Testis antigens that are expressed in many cancer types and are thought to contribute actively to malignancy. MAGE-A proteins are established regulators of certain cancer-associated transcription factors, including p53, and are activators of several RING finger-dependent ubiquitin E3 ligases. Here, we show that MAGE-A2 associates with MDM2, a ubiquitin E3 ligase that mediates ubiquitylation of more than 20 substrates including mainly p53, MDM2 itself, and MDM4, a potent p53 inhibitor and MDM2 partner that is structurally related to MDM2. We find that MAGE-A2 interacts with MDM2 via the N-terminal p53-binding pocket and the RING finger domain of MDM2 that is required for homo/hetero-dimerization and for E2 ligase interaction. Consistent with these data, we show that MAGE-A2 is a potent inhibitor of the E3 ubiquitin ligase activity of MDM2, yet it does not have any significant effect on p53 turnover mediated by MDM2. Strikingly, however, increased MAGE-A2 expression leads to reduced ubiquitylation and increased levels of MDM4. Similarly, silencing of endogenous MAGE-A expression diminishes MDM4 levels in a manner that can be rescued by the proteasomal inhibitor, bortezomid, and permits increased MDM2/MDM4 association. These data suggest that MAGE-A proteins can: (i) uncouple the ubiquitin ligase and degradation functions of MDM2; (ii) act as potent inhibitors of E3 ligase function; and (iii) regulate the turnover of MDM4. We also find an association between the presence of MAGE-A and increased MDM4 levels in primary breast cancer, suggesting that MAGE-A-dependent control of MDM4 levels has relevance to cancer clinically
3D Brownian Diffusion of Submicron-Sized Particle Clusters
We report on the translation and rotation of particle clusters made through
the combination of spherical building blocks. These clusters present ideal
model systems to study the motion of objects with complex shape. Because they
could be separated into fractions of well-defined configurations on a
sufficient scale and their overall dimensions were below 300 nm, the
translational and rotational diffusion coefficients of particle duplets,
triplets and tetrahedrons could be determined by a combination of polarized
dynamic light scattering (DLS) and depolarized dynamic light scattering (DDLS).
The use of colloidal clusters for DDLS experiments overcomes the limitation of
earlier experiments on the diffusion of complex objects near surfaces because
the true 3D diffusion can be studied. When the exact geometry of the complex
assemblies is known, different hydrodynamic models for calculating the
diffusion coefficient for objects with complex shapes could be applied. Because
hydrodynamic friction must be restricted to the cluster surface the so-called
shell model, in which the surface is represented as a shell of small friction
elements, was most suitable to describe the dynamics. A quantitative comparison
of the predictions from theoretical modeling with the results obtained by DDLS
showed an excellent agreement between experiment and theory
Nanofiltration of hormone mimicking trace organic contaminants
The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF)
membranes have been examined. Two NF membranes having different pore size were used in
laboratory-scale nanofiltration experiments with feed solutions spiked with a hormone mimicking
compound ¾ nonylphenol, tert-butyl phenol, or bisphenol A. Retention of the compounds was
determined at various solution chemistries, namely aqueous solution pH, ionic strength, and
presence of natural organic matter. The nanofiltration behavior of the selected hormone mimicking
compounds appears similar to that of natural hormones as reported in our previous work. While the
solution pH can dramatically influence the retention of hormone mimicking compounds by a loose
NF membrane, ionic strength does not affect the nanofiltration of such contaminants. However, in
the presence of natural organic matter in the feed solution, ionic strength appears to play a
significant role in solute-solute and solute-membrane interactions, resulting in increased retention
due to partitioning of the hormone mimicking compounds onto organic matter at a higher ionic
strength
Photodynamic Therapy of Tumors Can Lead to Development of Systemic Antigen-Specific Immune Response
Background:
The mechanism by which the immune system can effectively recognize and destroy tumors is dependent on recognition of tumor antigens. The molecular identity of a number of these antigens has recently been identified and several immunotherapies have explored them as targets. Photodynamic therapy (PDT) is an anti-cancer modality that uses a non-toxic photosensitizer and visible light to produce cytotoxic reactive oxygen species that destroy tumors. PDT has been shown to lead to local destruction of tumors as well as to induction of anti-tumor immune response.
Methodology/Principal Findings:
We used a pair of equally lethal BALB/c colon adenocarcinomas, CT26 wild-type (CT26WT) and CT26.CL25 that expressed a tumor antigen, β-galactosidase (β-gal), and we treated them with vascular PDT. All mice bearing antigen-positive, but not antigen-negative tumors were cured and resistant to rechallenge. T lymphocytes isolated from cured mice were able to specifically lyse antigen positive cells and recognize the epitope derived from beta-galactosidase antigen. PDT was capable of destroying distant, untreated, established, antigen-expressing tumors in 70% of the mice. The remaining 30% escaped destruction due to loss of expression of tumor antigen. The PDT anti-tumor effects were completely abrogated in the absence of the adaptive immune response.
Conclusion:
Understanding the role of antigen-expression in PDT immune response may allow application of PDT in metastatic as well as localized disease. To the best of our knowledge, this is the first time that PDT has been shown to lead to systemic, antigen- specific anti-tumor immunity.United States. National Cancer Institute (grant RO1CA/AI838801)United States. National Cancer Institute (grant R01AI050875
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