Cáncer localizado de próstata

Se analizaron 560 pacientes consecutivos con cáncer localizado de próstata tratados con radioterapia conformal tridimensional entre 1993 y 2001. La sobrevida global actuarial a los nueve años fue de 71%, y la sobrevida causa específica de 88%. La mortalidad cruda por cáncer de próstata fue de 4,8% mientras que la mortalidad por otras causas fue de 8,3%. La sobrevida libre de recaída bioquímica en función del grupo de riesgo fue de 83%, 68% y 41% a los nueve años, respectivamente para los grupos de riesgo bajo, intermedio y alto en 504 pacientes (p<0,05). La dosis mayor o igual a 72 Gy mejora el control bioquímico a los siete años en todos los grupos de riesgo aunque sólo es estadísticamente significativa en el grupo de riesgo alto (p<0,006). El modelo de Cox reveló que solamente el grupo de riesgo, la dosis total como variable continua y el antígeno prostático específico inicial como variable categórica fueron significativos. Cuando el modelo de Cox fue aplicado a los 188 pacientes de riesgo alto, el uso de la hormonoterapia de inducción o concomitante, o ambas, y la edad, resultaron además significativos. La tasa actuarial de complicaciones severas a diez años grados 3 y 4 (no hubo complicaciones grado 5) fue de 1,2% para las urinarias y de 1,4% para las digestivas. La radioterapia conformal tridimensional a altas dosis es un tratamiento efectivo y de baja morbilidad para el tratamiento del cáncer localizado de próstata

The ER luminal binding protein (BiP) mediates an increase in drought tolerance in soybean and delays drought-induced leaf senescence in soybean and tobacco

The ER-resident molecular chaperone BiP (binding protein) was overexpressed in soybean. When plants growing in soil were exposed to drought (by reducing or completely withholding watering) the wild-type lines showed a large decrease in leaf water potential and leaf wilting, but the leaves in the transgenic lines did not wilt and exhibited only a small decrease in water potential. During exposure to drought the stomata of the transgenic lines did not close as much as in the wild type, and the rates of photosynthesis and transpiration became less inhibited than in the wild type. These parameters of drought resistance in the BiP overexpressing lines were not associated with a higher level of the osmolytes proline, sucrose, and glucose. It was also not associated with the typical drought-induced increase in root dry weight. Rather, at the end of the drought period, the BiP overexpressing lines had a lower level of the osmolytes and root weight than the wild type. The mRNA abundance of several typical drought-induced genes [NAC2, a seed maturation protein (SMP), a glutathione-S-transferase (GST), antiquitin, and protein disulphide isomerase 3 (PDI-3)] increased in the drought-stressed wild-type plants. Compared with the wild type, the increase in mRNA abundance of these genes was less (in some genes much less) in the BiP overexpressing lines that were exposed to drought. The effect of drought on leaf senescence was investigated in soybean and tobacco. It had previously been reported that tobacco BiP overexpression or repression reduced or accentuated the effects of drought. BiP overexpressing tobacco and soybean showed delayed leaf senescence during drought. BiP antisense tobacco plants, conversely, showed advanced leaf senescence. It is concluded that BiP overexpression confers resistance to drought, through an as yet unknown mechanism that is related to ER functioning. The delay in leaf senescence by BiP overexpression might relate to the absence of the response to drought

Mixing in confined stratified aquifers

Spatial variability in a flow field leads to spreading of a tracer plume. The effect of microdispersion is to smooth concentration gradients that exist in the system. The combined effect of these two phenomena leads to an 'effective' enhanced mixing that can be asymptotically quantified by an effective dispersion coefficient (i.e. Taylor dispersion). Mixing plays a fundamental role in driving chemical reactions. However, at pre-asymptotic times it is considerably more difficult to accurately quantify these effects by an effective dispersion coefficient as spreading and mixing are not the same (but intricately related). In this work we use a volume averaging approach to calculate the concentration distribution of an inert solute release at pre-asymptotic times in a stratified formation. Mixing here is characterized by the scalar dissipation rate, which measures the destruction of concentration variance. As such it is an indicator for the degree of mixing of a system. We study pre-asymptotic solute mixing in terms of explicit analytical expressions for the scalar dissipation rate and numerical random walk simulations. In particular, we divide the concentration field into a mean and deviation component and use dominant balance arguments to write approximate governing equations for each, which we then solve analytically. This allows us to explicitly evaluate the separate contributions to mixing from the mean and the deviation behavior. We find an approximate, but accurate expression (when compared to numerical simulations) to evaluate mixing. Our results shed some new light on the mechanisms that lead to large scale mixing and allow for a distinction between solute spreading, represented by the mean concentration, and mixing, which comes from both the mean and deviation concentrations, at pre-asymptotic times. © 2010 Elsevier B.V. All rights reserved.Peer Reviewe