115 research outputs found
Multiplication of Distributions and Nonperturbative Calculations of Transition Probabilities
In a mathematical context in which one can multiply distributions the
"`formal"' nonperturbative canonical Hamiltonian formalism in Quantum Field
Theory makes sense mathematically, which can be understood a priori from the
fact the so called "`infinite quantities"' make sense unambiguously (but are
not classical real numbers). The perturbation series does not make sense. A
novelty appears when one starts to compute the transition probabilities. The
transition probabilities have to be computed in a nonperturbative way which, at
least in simplified mathematical examples (even those looking like
nonrenormalizable series), gives real values between 0 and 1 capable to
represent probabilities. However these calculations should be done numerically
and we have only been able to compute simplified mathematical examples due to
the fact these calculations appear very demanding in the physically significant
situation with an infinite dimensional Fock space and the QFT operators
Thrombosis Is Reduced by Inhibition of COX-1, but Unaffected by Inhibition of COX-2, in an Acute Model of Platelet Activation in the Mouse
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Major Cellular and Physiological Impacts of Ocean Acidification on a Reef Building Coral
As atmospheric levels of CO2 increase, reef-building corals are under greater stress from both increased sea surface temperatures and declining sea water pH. To date, most studies have focused on either coral bleaching due to warming oceans or declining calcification due to decreasing oceanic carbonate ion concentrations. Here, through the use of physiology measurements and cDNA microarrays, we show that changes in pH and ocean chemistry consistent with two scenarios put forward by the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, before affects on biomineralisation are apparent at the phenotype level. Under high CO2 conditions corals at the phenotype level lost over half their Symbiodinium populations, and had a decrease in both photosynthesis and respiration. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrate upregulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur before impacts on calcification
Adaptive Radiation in Mediterranean Cistus (Cistaceae)
lineage consists of
12 species primarily distributed in Mediterranean habitats and
is herein subject to analysis. lineages), which display asymmetric
characteristics: number of species (2 vs. 10), leaf morphologies
(linear vs. linear to ovate), floral characteristics (small,
three-sepalled vs. small to large, three- or five-sepalled
flowers) and ecological attributes (low-land vs. low-land to
mountain environments). A positive phenotype-environment
correlation has been detected by historical reconstructions of
morphological traits (leaf shape, leaf labdanum content and leaf
pubescence). Ecological evidence indicates that modifications of
leaf shape and size, coupled with differences in labdanum
secretion and pubescence density, appear to be related to
success of new species in different Mediterranean habitats.
The Use and Economic Value of Manna grass (Glyceria) in Poland from the Middle Ages to the Twentieth Century
Strong isolation by distance argues for separate population management of endangered blue duck (Hymenolaimus malacorhynchos)
BAX-depleted retinal ganglion cells survive and become quiescent following optic nerve damage
Removal of the Bax gene from mice completely protects the somas of retinal ganglion cells (RGCs) from apoptosis following optic nerve injury. This makes BAX a promising therapeutic target to prevent neurodegeneration. In this study, Bax+/− mice were used to test the hypothesis that lowering the quantity of BAX in RGCs would delay apoptosis following optic nerve injury. RGCs were damaged by performing optic nerve crush (ONC) and then immunostaining for phospho-cJUN, and quantitative PCR were used to monitor the status of the BAX activation mechanism in the months following injury. The apoptotic susceptibility of injured cells was directly tested by virally introducing GFP-BAX into Bax−/− RGCs after injury. The competency of quiescent RGCs to reactivate their BAX activation mechanism was tested by intravitreal injection of the JNK pathway agonist, anisomycin. Twenty-four weeks after ONC, Bax+/− mice had significantly less cell loss in their RGC layer than Bax+/+ mice 3 weeks after ONC. Bax+/− and Bax+/+ RGCs exhibited similar patterns of nuclear phospho-cJUN accumulation immediately after ONC, which persisted in Bax+/− RGCs for up to 7 weeks before abating. The transcriptional activation of BAX-activating genes was similar in Bax+/− and Bax+/+ RGCs following ONC. Intriguingly, cells deactivated their BAX activation mechanism between 7 and 12 weeks after crush. Introduction of GFP-BAX into Bax−/− cells at 4 weeks after ONC showed that these cells had a nearly normal capacity to activate this protein, but this capacity was lost 8 weeks after crush. Collectively, these data suggest that 8–12 weeks after crush, damaged cells no longer displayed increased susceptibility to BAX activation relative to their naïve counterparts. In this same timeframe, retinal glial activation and the signaling of the pro-apoptotic JNK pathway also abated. Quiescent RGCs did not show a timely reactivation of their JNK pathway following intravitreal injection with anisomycin. These findings demonstrate that lowering the quantity of BAX in RGCs is neuroprotective after acute injury. Damaged RGCs enter a quiescent state months after injury and are no longer responsive to an apoptotic stimulus. Quiescent RGCs will require rejuvenation to reacquire functionality
Role of prostacyclin in the cardiovascular response to thromboxane A2
Thromboxane (Tx) A2 is a vasoconstrictor and platelet agonist. Aspirin affords cardioprotection through inhibition of TxA2 formation by platelet cyclooxygenase (COX-1). Prostacyclin (PGI2) is a vasodilator that inhibits platelet function. Here we show that injury-induced vascular proliferation and platelet activation are enhanced in mice that are genetically deficient in the PGI2 receptor (IP) but are depressed in mice genetically deficient in the TxA2 receptor (TP) or treated with a TP antagonist. The augmented response to vascular injury was abolished in mice deficient in both receptors. Thus, PGI2 modulates platelet-vascular interactions in vivo and specifically limits the response to TxA2. This interplay may help explain the adverse cardiovascular effects associated with selective COX-2 inhibitors, which, unlike aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), inhibit PGI2 but not TxA2
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