179 research outputs found
Importance of Extracellular Enzymes for Biogeochemical Processes in Temporary River Sediments during Fluctuating DryâWet Conditions
The International Law of Secession and the Protection of the Human Rights of Oppressed Sub-State Groups: Yesterday, Today and Tomorrow
This paper focuses on significant patterns/features in the historical development of the international law of secession and its contribution over time (or the lack thereof) to the struggle to afford greater protection to oppressed sub-state groups the world over. It was Crawford Young who once observed that âthe state as an analytical quarry is an elusive and complex prey.â With the necessary modifications, this observation applies with almost equal force to the international law of secession. Complexity and confusion loom too large in this area of international law. For example, there is, at best, little clarity in the literature of the discipline of international law and in related fields of study regarding the existence or otherwise of an international legal entitlement to secession in favor of even the most highly oppressed and subjugated sub-state groups
PHD3 regulates differentiation, tumour growth and angiogenesis in pancreatic cancer
pancreatic cance
Caloric restriction counteracts age-dependent changes in prolyl-4-hydroxylase domain (PHD) 3 expression
Caloric restriction remains the most reproducible measure known to extend life span or diminish age-associated changes. Previously, we have described an elevated expression of the prolyl-4-hydroxylase domain (PHD) 3 with increasing age in mouse and human heart. PHDs modulate the cellular response towards hypoxia by regulating the stability of the α-subunit of the transcriptional activator hypoxia inducible factor (HIF). In the present study we demonstrate that elevated PHD3, but not PHD1 or PHD2, expression is not restricted to the heart but does also occur in rat skeletal muscle and liver. Elevated expression of PHD3 is counteracted by a decrease in caloric intake (40% caloric restriction applied for 6 months) in all three tissues. Age-associated changes in PHD3 expression inversely correlated with the expression of the HIF-target gene macrophage migration inhibitory factor (MIF), which has been previously described to be involved in cellular HIF-mediated anti-ageing effects. These data give insight into the molecular consequences of caloric restriction, which influences hypoxia-mediated gene expression via PHD3
Introduction of a new model for time-continuous and non-contact investigations of in-vitro thrombolysis under physiological flow conditions
<p>Abstract</p> <p>Background</p> <p>Thrombolysis is a dynamic and time-dependent process influenced by the haemodynamic conditions. Currently there is no model that allows for time-continuous, non-contact measurements under physiological flow conditions. The aim of this work was to introduce such a model.</p> <p>Methods</p> <p>The model is based on a computer-controlled pump providing variable constant or pulsatile flows in a tube system filled with blood substitute. Clots can be fixed in a custom-built clot carrier within the tube system. The pressure decline at the clot carrier is measured as a novel way to measure lysis of the clot. With different experiments the hydrodynamic properties and reliability of the model were analyzed. Finally, the lysis rate of clots generated from human platelet rich plasma (PRP) was measured during a one hour combined application of diagnostic ultrasound (2 MHz, 0.179 W/cm<sup>2</sup>) and a thrombolytic agent (rt-PA) as it is commonly used for clinical sonothrombolysis treatments.</p> <p>Results</p> <p>All hydrodynamic parameters can be adjusted and measured with high accuracy. First experiments with sonothrombolysis demonstrated the feasibility of the model despite low lysis rates.</p> <p>Conclusions</p> <p>The model allows to adjust accurately all hydrodynamic parameters affecting thrombolysis under physiological flow conditions and for non-contact, time-continuous measurements. Low lysis rates of first sonothrombolysis experiments are primarily attributable to the high stability of the used PRP-clots.</p
Where Itâs at Really Matters: In Situ In Vivo Vascular Endothelial Growth Factor Spatially Correlates with Electron Paramagnetic Resonance pO2 Images in Tumors of Living Mice
Purpose: Tumor microenvironments show remarkable tumor pO_{2} heterogeneity, as seen in prior EPR pO_{2} images (EPROI). pO_{2} correlation with hypoxia response proteins is frustrated by large rapid pO2 changes with position.
Procedures: To overcome this limitation, biopsies stereotactically located in the EPROI were used to explore the relationship between vascular endothelial growth factor A (VEGF) concentrations in living mouse tumors and the local EPROI pO_{2}.
Results: Quantitative ELISA VEGF concentrations correlated (pâ=â0.0068 to 0.019) with mean pO_{2}, median pO_{2}, and the fraction of voxels in the biopsy volume with pO_{2} less than 3, 6, and 10 Torr.
Conclusions: This validates EPROI hypoxic fractions at the molecular level and provides a new paradigm for the assessment of the relationship, in vivo, between hypoxia and hypoxia response proteins. When translated to human subjects, this will enhance understanding of human tumor pathophysiology and cancer response to therapy
Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems
Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers
Understanding complexity in the HIF signaling pathway using systems biology and mathematical modeling
Hypoxia is a common micro-environmental stress which is experienced by cells during a range of physiologic and pathophysiologic processes. The identification of the hypoxia-inducible factor (HIF) as the master regulator of the transcriptional response to hypoxia transformed our understanding of the mechanism underpinning the hypoxic response at the molecular level and identified HIF as a potentially important new therapeutic target. It has recently become clear that multiple levels of regulatory control exert influence on the HIF pathway giving the response a complex and dynamic activity profile. These include positive and negative feedback loops within the HIF pathway as well as multiple levels of crosstalk with other signaling pathways. The emerging model reflects a multi-level regulatory network that affects multiple aspects of the physiologic response to hypoxia including proliferation, apoptosis, and differentiation. Understanding the interplay between the molecular mechanisms involved in the dynamic regulation of the HIF pathway at a systems level is critically important in defining new appropriate therapeutic targets for human diseases including ischemia, cancer, and chronic inflammation. Here, we review our current knowledge of the regulatory circuits which exert influence over the HIF response and give examples of in silico model-based predictions of the dynamic behaviour of this system
Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems
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