Vanadium pentoxide: an oxidative stress agent which disturbs glutathione conjugates metabolization in Saccharomyces cerevisiae UE-ME3

Under physiological conditions the vanadium can be detected in the oxidation state V (+5), a very toxic specie. In this study we used a wine wild-type Saccharomyces cerevisiae UE-ME3 to assess how eukaryotic cells respond to V2O5. Yeast cells in exponential phase were inoculated into YEPD medium with 2% (w / v) glucose and allowed to grow in the absence or presence of 0.5 to 2.0 mM V2O5 during 72 h. The results show that the cellular environment became more oxidizing, cell damages increase and failures in the transport and excretion of amino acids to the vacuole ocurr in yeast cells grown in the presence of vanadium (+5), as can be inferred by the decrease of GSH/GSSG ratio, increase of MDA cytoplasmic level and the sharp decrease of g-GT activity observed. Although there was an apparent response anti-stress to V2O5, reflected in an increase of GR activity in all trials of metal exposure and of GPx in cells exposed to 1.5 and 2.0 mM, this was probably mitigated by the decrease in activity G6PD and consequent availability of NADPH which compromise cell viability

Cutaneous necrobiotic xanthogranuloma (NXG)--successfully treated with low dose chlorambucil.

Eur J Dermatol. 2001 Sep-Oct;11(5):458-62. Cutaneous necrobiotic xanthogranuloma (NXG)--successfully treated with low dose chlorambucil. Machado S, Alves R, Lima M, Leal I, Massa A. SourceService of Dermatology, Hospital Geral Santo António, Rua D. Manuel II, Edifício ex: Cicap, 4099-001 Porto, Portugal. [email protected] Abstract We report a case of necrobiotic xanthogranuloma in a 51 year-old white male patient presenting with a 6-year history of multiple indurated violaceous nodules and plaques involving the eyelids, trunk and extremities. He had an associated paraproteinemia (Ig G lambda), elevated sedimentation rate, cryoglobulinemia and hypocomplementemia. No extracutaneous involvement was detected. He was successfully treated with chlorambucil (2 mg/d for 7 months), leading to disappearance of all skin lesions

Sensoriamento remoto e geoprocessamento aplicados ao zoneamento geoambiental: bacia hidrográfica do Açude Camará - PB.

A diversidade de paisagens da bacia hidrográfica da barragem Camará, principalmente no que se refere às formas de relevo, de solos e de sistemas de produção, induziu a realização deste zoneamento geoambiental. Sua importância reside nas preocupações com a conservação do meio ambiente e com o desenvolvimento sócio-econômico e a preservação dos recursos naturais na área em busca do desenvolvimento sustentável. Este trabalho teve como objetivo criar um banco de dados atualizado e, com o zoneamento geoambiental, realizar uma análise simplifi cada dos atributos fi siográfi cos, solo, clima, relevo e uso da terra, separando e descrevendo unidades da paisagem, suas potencialidades e limitações. Foram utilizadas nesta pesquisa imagem do satélite CBERS e técnicas de geoprocessamento a partir do programa SPRING, bases para os trabalhos descritivos em campo. A partir das informações de solo, relevo e uso da terra foram descritas as áreas susceptíveis a degradação ambiental

Group selection models in prebiotic evolution

The evolution of enzyme production is studied analytically using ideas of the group selection theory for the evolution of altruistic behavior. In particular, we argue that the mathematical formulation of Wilson's structured deme model ({\it The Evolution of Populations and Communities}, Benjamin/Cumings, Menlo Park, 1980) is a mean-field approach in which the actual environment that a particular individual experiences is replaced by an {\it average} environment. That formalism is further developed so as to avoid the mean-field approximation and then applied to the problem of enzyme production in the prebiotic context, where the enzyme producer molecules play the altruists role while the molecules that benefit from the catalyst without paying its production cost play the non-altruists role. The effects of synergism (i.e., division of labor) as well as of mutations are also considered and the results of the equilibrium analysis are summarized in phase diagrams showing the regions of the space of parameters where the altruistic, non-altruistic and the coexistence regimes are stable. In general, those regions are delimitated by discontinuous transition lines which end at critical points.Comment: 22 pages, 10 figure

Dirac-Surface-State-Dominated Spin to Charge Current Conversion in the Topological Insulator (Bi0.22Sb0.78)2Te3(Bi_{0.22}Sb_{0.78})_2Te_3 Films at Room Temperature

We report the spin to charge current conversation in an intrinsic topological insulator (TI) $(Bi_{0.22}Sb_{0.78})_2Te_3$ film at room temperature. The spin currents are generated in a thin layer of permalloy (Py) by two different processes, spin pumping (SPE) and spin Seebeck effects (SSE). In the first we use microwave-driven ferromagnetic resonance of the Py film to generate a SPE spin current that is injected into the TI $(Bi_{0.22}Sb_{0.78})_2Te_3$ layer in direct contact with Py. In the second we use the SSE in the longitudinal configuration in Py without contamination by the Nernst effect made possible with a thin NiO layer between the Py and $(Bi_{0.22}Sb_{0.78})_2Te_3$ layers. The spin-to-charge current conversion is attributed to the inverse Edelstein effect (IEE) made possible by the spin-momentum locking in the electron Fermi contours due to the Rashba field. The measurements by the two techniques yield very similar values for the IEE parameter, which are larger than the reported values in the previous studies on topological insulators.Comment: 18 pages and 7 figure

A Population Genetic Approach to the Quasispecies Model

A population genetics formulation of Eigen's molecular quasispecies model is proposed and several simple replication landscapes are investigated analytically. Our results show a remarcable similarity to those obtained with the original kinetics formulation of the quasispecies model. However, due to the simplicity of our approach, the space of the parameters that define the model can be explored. In particular, for the simgle-sharp-peak landscape our analysis yelds some interesting predictions such as the existence of a maximum peak height and a mini- mum molecule length for the onset of the error threshold transition.Comment: 16 pages, 4 Postscript figures. Submited to Phy. Rev.