Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion-adsorption model of uranium uptake.

Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described. Unlike the classic diffusion-adsorption (D-A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10(-12) cm(2)s(-1). Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved.

Improvement of therapeutic compliance in haemodialysis patients with poor phosphorus control and adherence to treatment with binders: COMQUELFOS study.

BACKGROUND: The effectiveness of phosphate binders in daily practice is directly related to therapeutic compliance (TC) by the patient. The goal of this study was to analyse the TC of haemodialysis patients with hyperphosphatemia and its influence on serum phosphorus for 6 months follow up. METHODS: 181 patients were included, who had mean initial phosphate levels (P) >5mg/dl. TC with different phosphate binders was evaluated, considering non-adherent patients those who had <75% of TC, SMAQ scale score of "non-adherent"(Table 1), and P>5mg/dl. Patients who were adherent at baseline visit (BV) left the study, the rest continued to V5 (6 months). TC at baseline and during the follow up (V1-V5) was analysed. Phosphate binders and the evolution of phosphataemia based on treatment were assessed. RESULTS: 103 male and 78 female patients were evaluated, with a mean age of 59.9 (21-86) years. Of these, 39.2% (n=71) were adherent in the BV. Patients older than 60 years of age were more adherent than younger ones (P=.019).Table 6 specifies the causes of non-compliance. The remaining 60.8% of patients (n=110), were non-adherent and continued through to the end of the study. An average of 27.2% of these patients became adherent during the course of the study. Table 7 shows the relative levels of P with TC over successive visits. At the end of the study, mean P levels had decreased by 1.26mg/dl (P<.0001). CONCLUSION: Among HD patients with poor P level control, there is a low level of adherence with phosphorus binder treatment, at 39.2%. Compliance and phosphataemia are improved with different strategies. The decrease of P is higher in adherent patients than in non-adherent patients.

Alternaria brasiliensis sp. nov., a leaf pathogen on Phaseolus vulgaris.

Alternaria brasiliensis sp. nov., was isolated from leaves of common bean, Phaseolus vulgaris L., showing punctiform non concentric leaf spots of brown color. Besides the symptomatological differences, the new Alternaria species presents distinct type of arrangement of conidia chain, body and beak size. The disease was observed in Montanha county, State of Espirito Santo, Brazil, but not yet reported in the literature. The causal agent of the disease is now described by the first time. The epithet used here is referring to the country where the species has been found.

Variation in tomato host response to Bemisia tabaci (Hemiptera: Aleyrodidae) in relation to acyl sugar content and presence of the nematode and potato aphid resistance gene Mi.

Two commercial cultivars of tomato, Alta and Peto 95, the accession line number LA716 of Lycopersicon pennellii and lines 94GH-006 and 94GH-033 (backcrosses between Peto 95 and LA716), with different leaf acyl sugar contents were screened for resistance to Bemisia argentifolii Bellows & Perring (corresponding to the Spanish B-biotype of Bemisia tabaci (Gennadius)), in greenhouse- and field-no-choice experiments. There was no oviposition on LA716 (with the highest acyl sugar content) while the greatest fecundity and fertility values were observed on the cultivar Alta (no acyl sugar content). However, no clear relationship was found between the low acyl sugar content in the other tomato cultivars tested and whitefly reproduction. Thus, resistance to B. tabaci did not appear to correlate with acyl sugar content below a threshold level of 37.8 microg cm-2 leaf. In a greenhouse choice-assay, B. tabaci exhibited reduced host preference and reproduction on the commercial tomato cultivars Motelle, VFN8 and Ronita all of which carry the Mi gene resistance to Meloidogyne nematodes and the aphid Macrosiphum euphorbiae (Thomas), than on the Mi-lacking cultivars Moneymaker, Rio Fuego and Roma. When data of Mi-bearing plants were pooled, the mean values for daily infestation and pupal production of B. tabaci were significantly lower than those of Mi-lacking plants. This reflected a level of antixenosis- and antibiosis-based resistance in commercial tomato and indicated that Mi, or another closely linked gene, might be implicated in a partial resistance which was not associated either with the presence of glandular trichomes or their exudates. These findings support the general hypothesis for the existence of similarities among the resistance mechanisms to whiteflies, aphids and nematodes in commercial tomato plants.