Modulation of dendritic cell maturation by ribotoxic and oxidative stress

Dendritic cells (DC) are known to be vital to the immune response, priming naive T cells to antigen specific proliferation. Dendritic cells in their immature state have a unique capacity to ingest large numbers of antigens via macopinocytosis. After receiving an appropriate signal they mature to an antigen presenting and T cell stimulatory state, displaying antigens bound to MHC molecules and up-regulating expression of co-stimulatory molecules. It is now well established that DC are matured by recognition of conserved molecular pattern on pathogenic organisms, often referred to as PAMPs (pathogen associated molecular patterns). In addition DC can mature in response to inflammatory cytokines such as TNF-a and IL-1 p. In this thesis an alternative DC maturation pathway is proposed, in which DC mature in response to interference with the ribosomal machinery, particularly 28S rRNA. The stress kinases are also proposed to signal any changes in 28S rRNA status within the DC. To test this hypothesis DC are incubated with ribotoxic compounds and maturation is measured by phenotype analysis, T cell stimulation and cytokine release. The results show that ribotoxic compounds can at low doses cause partial activation of DC. The proposal is then made that this route of DC activation may signal viral infection of DC, leading to maturation in response. In addition low level redox stress is shown to act in synergy with LPS to enhance T cell proliferation and cytokine release. Finally necrotic lymphocyte treated DC are shown to enhance T cell proliferation. Therefore the conclusion is made that stress per se acts as an auxiliary mechanism of enhancing immune responses, acting in synergy with receptor driven immune activation. The 28S rRNA pathway however is proposed as a major route of viral activation of DC

Condensation and partial pressure change as a major cause of airflow: experimental evidence

The dominant model of atmospheric circulation is based on the notion that hot air rises, creating horizontal winds. A second major driver has been proposed in the biotic pump theory (BPT), by which intense condensation is the prime cause of surface winds from ocean to land. Critics of the BPT argue that air movement resulting from condensation is isotropic. This paper explores the physics of water condensation under mild atmospheric conditions, within a purpose-designed square-section 4.8m-tall closed-system structure. The data show a highly significant correlation (R2 >0.96, p value <0.001) between observed airflows and partial pressure changes from condensation. The assumption that condensation of water vapour is always isotropic is therefore incorrect

The equations of motion for moist atmospheric air

How phase transitions affect the motion of moist atmospheric air remains controversial. In the early 2000s two distinct differential equations of motion were proposed. Besides their contrasting formulations for the acceleration of condensate, the equations differ concerning the presence/absence of a term equal to the rate of phase transitions multiplied by the difference in velocity between condensate and air. This term was interpreted in the literature as the "reactive motion" associated with condensation. The reasoning behind this "reactive motion" was that when water vapor condenses and droplets begin to fall the remaining gas must move upwards to conserve momentum. Here we show that the two contrasting formulations imply distinct assumptions about how gaseous air and condensate particles interact. We show that these assumptions cannot be simultaneously applicable to condensation and evaporation. "Reactive motion" leading to an upward acceleration of air during condensation does not exist. The "reactive motion" term can be justified for evaporation only; it describes the downward acceleration of air. We emphasize the difference between the equations of motion (i.e., equations constraining velocity) and those constraining momentum (i.e., equations of motion and continuity combined). We show that, owing to the imprecise nature of the continuity equations, consideration of total momentum can be misleading and that this led to the "reactive motion" controversy. Finally, we provide a revised and generally applicable equation for the motion of moist air.Comment: 11 pages, two figure

Further experimental evidence that condensation is a major cause of airflow

This paper further explores the physics of water condensation, using an experimental structure designed for that purpose. The data show a highly significant correlation (R2 >0.94, p value <0.001) between observed airflows and partial pressure changes from condensation, when the results of different experiments are pooled. Changes in air density on cooling provide insufficient energy to account for the airflow. The finding is that the kinetic energy of the chilled air falls short by an order of magnitude, even to move a relatively small proportion of the 20 kg of air contained within the structure. Meanwhile the physics of condensation indicate a surplus of kinetic energy is made available from the air surrounding the locus of condensation. At low rates of condensation a considerable proportion of the available kinetic energy in the enclosed air is absorbed in friction and turbulence. That proportion reduces with higher rates of condensation

The Role of Ecosystems in Determining Climate: The Special Case of The Amazon Rainforests

Titulo en español:  La Importancia de los Ecosistemas en la Determinación del Clima: Caso Especial los Bosques de la AmazoniaRESUME:The summer floods in England, following deluges of rain more resonant of the Amazon, the searing, deadly heat in Southern Europe, with temperatures at times exceeding 45°C, should be enough to silence those who stalwartly maintain that we are experiencing no more than natural swings in climate. Those scep- tics, who have insisted that long term changes in the Earth’s orbit as well as in the flux of sunlight are accountable for the extreme weather and global warm- ing, have basically been routed.Titulo en español:  La Importancia de los Ecosistemas en la Determinación del Clima: Caso Especial los Bosques de la AmazoniaRESUME:The summer floods in England, following deluges of rain more resonant of the Amazon, the searing, deadly heat in Southern Europe, with temperatures at times exceeding 45°C, should be enough to silence those who stalwartly maintain that we are experiencing no more than natural swings in climate. Those scep- tics, who have insisted that long term changes in the Earth’s orbit as well as in the flux of sunlight are accountable for the extreme weather and global warm- ing, have basically been routed

Vientos y lluvia: El papel de la bomba biótica

In 2007, Anastassia Makarieva and Victor Gorshkov came up with the Biotic Pump Theory (Makarieva A. a., 2007). The two scientists, mathematician/physicists at the Petersburg Nuclear Physics Institute, St Petersburg, Russia, described the Biotic Pump Theory (BPT) in terms of the fundamental laws of physics pertaining to the phase change when water evaporates and then condenses through the process of cloud-forming, as humid air rises in the troposphere and chills with altitude. The degree of water vapour saturation follows the Clausius-Clapeyron equation for ideal gases, taking into account temperature (Kelvin), relative humidity and barometric pressure.En 2007, Anastassia Makarieva y Victor Gorshkov elaboraron la Teoría de la Bomba Biótica (Makarieva A. a., 2007). Los dos científicos, matemáticos/físicos del Instituto de Física Nuclear de San Petersburgo, Rusia, describieron la Teoría de la Bomba Biótica (BPT) en términos de las leyes fundamentales de la física relativas al cambio de fase cuando el agua se evapora y luego se condensa a través del proceso de formación de nubes, a medida que el aire húmedo se eleva en la troposfera y se enfría con la altitud. El grado de saturación del vapor de agua sigue la ecuación de Clausius-Clapeyron para los gases ideales, teniendo en cuenta la temperatura (Kelvin), la humedad relativa y la presión barométrica

Climate Models Don’t Give Us The Full Story

Titulo en español:Modelos del Clima nos han Dado la Historia ImcompletaRESUME:  In the debate about global warming we forget at our peril the role of ecosystems in giving us a climate we can live with. Life co-evolving with our planet over thousands of millions of years has created an envi- ronment apt for millions upon millions of species, from bacteria to the massive whale or towering red- wood trees. In its totality and working together through complex, even endogenous, symbiotic re- lationships, life gives us a relatively stable climate, modifying the amount of heat stored at the Earth’s surface, regulating the clouds that bring rain to the continents, and changing the colour of the Earth so that it differentially absorbs energy from the Sun or on the contrary, reflects it back into space.Titulo en español:Modelos del Clima nos han Dado la Historia ImcompletaRESUME:  In the debate about global warming we forget at our peril the role of ecosystems in giving us a climate we can live with. Life co-evolving with our planet over thousands of millions of years has created an envi- ronment apt for millions upon millions of species, from bacteria to the massive whale or towering red- wood trees. In its totality and working together through complex, even endogenous, symbiotic re- lationships, life gives us a relatively stable climate, modifying the amount of heat stored at the Earth’s surface, regulating the clouds that bring rain to the continents, and changing the colour of the Earth so that it differentially absorbs energy from the Sun or on the contrary, reflects it back into space

How the Biotic Pump links the hydrological and the rainforest to climate : ¿Is it for real? ¿How can we prove it?

La teoría de la bomba biótica , establece que la primera fuerza motriz de los vientos de superficie, sobre todo en los trópicos , es inducida por los cambios negativos en la presión atmosférica causada por la condensación de vapor de agua cuando las nubes se forman. Una alta velocidad de condensación es necesaria y por lo tanto, la teoría requiere que una alta evapotranspiración de grandes áreas de bosques que proporcionan el "combustible" para el proceso. Por consiguiente, la teoría va en contra de la visión tradicional , como se presentó en los modelos climáticos , que los vientos de superficie son los únicos productos de diferencias de calentamiento de la superficie, así como de la liberación del calor latente durante el proceso de condensación. De hecho , Makarieva y sus colegas afirman que las transiciones en las fases de agua juegan un papel más importante en el impulso de la dinámica atmosférica de lo que se reconoce actualmente.the Biotic Pump Theory, as set forward by Drs. Makarieva and Gorshkov, states that the primary force driving surface winds, certainly in the tropics, is induced by the negative changes in atmospheric pressure caused by condensation of water vapour when clouds form. A high rate of condensation is necessary and therefore the theory requires that a suffciently high rate of evapotranspiration from large areas of forest provides the "fuel" for the process. The theory therefore runs contrary to the traditional view, as introduced in climate models, that surface winds are the sole products of differences in surface heating as well as of latent heat release during the process of condensation. Indeed, Makarieva and her colleagues claim that transitions in the phases of water play a far more important role in driving atmospheric dynamics than is currently recognise