EFFECTS OF SILICON ON ALLEVIATING ARSENIC TOXICITY IN MAIZE PLANTS

Arsenic is a metalloid highly toxic to plants and animals, causing reduced plant growth and various health problems for humans and animals. Silicon, however, has excelled in alleviating stress caused by toxic elements in plants. The aim of this study was to investigate the effects of Si in alleviating As stress in maize plants grown in a nutrient solution and evaluate the potential of the spectral emission parameters and the red fluorescence (Fr) and far-red fluorescence (FFr) ratio obtained in analysis of chlorophyll fluorescence in determination of this interaction. An experiment was carried out in a nutrient solution containing a toxic rate of As (68 μmol L-1) and six increasing rates of Si (0, 0.25, 0.5, 1.0, 1.5, and 2.0 mmol L-1). Dry matter production and concentrations of As, Si, and photosynthetic pigments were then evaluated. Chlorophyll fluorescence was also measured throughout plant growth. Si has positive effects in alleviating As stress in maize plants, evidenced by the increase in photosynthetic pigments. Silicon application resulted in higher As levels in plant tissue; therefore, using Si for soil phytoremediation may be a promising choice. Chlorophyll fluorescence analysis proved to be a sensitive tool, and it can be successfully used in the study of the ameliorating effects of Si in plant protection, with the Fr/FFr ratio as the variable recommended for identification of temporal changes in plants.

Genesis, Characterization, and Classification of Mangrove Soils in the Subaé River Basin, Bahia, Brazil

ABSTRACT Preservation of mangroves, a very significant ecosystem from a social, economic, and environmental viewpoint, requires knowledge on soil composition, genesis, morphology, and classification. These aspects are of paramount importance to understand the dynamics of sustainability and preservation of this natural resource. In this study mangrove soils in the Subaé river basin were described and classified and inorganic waste concentrations evaluated. Seven pedons of mangrove soil were chosen, five under fluvial influence and two under marine influence and analyzed for morphology. Samples of horizons and layers were collected for physical and chemical analyses, including heavy metals (Pb, Cd, Mn, Zn, and Fe). The moist soils were suboxidic, with Eh values below 350 mV. The pH level of the pedons under fluvial influence ranged from moderately acid to alkaline, while the pH in pedons under marine influence was around 7.0 throughout the profile. The concentration of cations in the sorting complex for all pedons, independent of fluvial or marine influence, indicated the following order: Na+>Mg2+>Ca2+>K+. Mangrove soils from the Subaé river basin under fluvial and marine influence had different morphological, physical, and chemical characteristics. The highest Pb and Cd concentrations were found in the pedons under fluvial influence, perhaps due to their closeness to the mining company Plumbum, while the concentrations in pedon P7 were lowest, due to greater distance from the factory. For containing at least one metal above the reference levels established by the National Oceanic and Atmospheric Administration (United States Environmental Protection Agency), the pedons were classified as potentially toxic. The soils were classified as Gleissolos Tiomórficos Órticos (sálicos) sódico neofluvissólico in according to the Brazilian Soil Classification System, indicating potential toxicity and very poor drainage, except for pedon P7, which was classified in the same subgroup as the others, but different in that the metal concentrations met acceptable standards.

Elements traça en esfalerites i galenes del dipòsit de Cierco (Pb-Zn). Alta Ribagorça, Pirineu Central

El diposit consisteix en dos filons E-W, tallats per un altre N-S. El rebliment filonia ès zonat amb esfalerita- galena-calcita als nivells profunds i galena-baritina als superiors. Els elements traça en esfalerites i galenes, plenament separades, han estat analitzats mitjancant fluorescència de raigs X. Els resultats mostren que l'esfalerita concentra la majoria d'elements traça, preferentment Fe, Co, Cd, Sn, Sb, Ga, Cu, Ge i Ag, amb una bona correlació entre els sis primers. La galena concentra únicament Sb, Ag i As, amb bona correlació entre els dos primers. Els continguts en elements traça estan homogèniament distribuits en tot el diposit.

Evaluation of the toxicity of different metal compounds in the developing brain using aggregating cell cultures as a model.

To evaluate their toxicity in the developing brain, eight metal compounds, [bismuth sodium tartrate (BiNA-tartrate), CdCl(2), CoCl(2), HgCl(2), dimethyl mercury, NiCl(2), TlCl and triethyltin chloride (TET)] were tested in aggregating cell cultures of foetal rat telencephalon. The compounds were applied to the cultures continuously, either during an early developmental stage (between days 5 and 14) or during and advanced stage of maturation (between days 24 and 34). Changes in the activities of cell type-specific enzymes were used as a criterion for toxicity. A general cytotoxic effect was observed after treatment with either CdCl(2), HgCl(2) or TET at 10(-6)m, and with TlCl at 10(-5)m. Selective effects were found with BiNa-tartrate and dimethylmercury. CoCl(2) did not modify the parameters tested, whereas a stimulant effect was found with NiCl(2). The effects of several compounds were development dependent: HgCl(2), TET and TlCl were more toxic in immature cultures, whereas BiNa-tartrate, dimethylmercury and NiCl(2) were more effective in differentiated cultures.

Liver, gastrointestinal and cardiac toxicity in intermediate hepatocellular carcinoma treated with PRECISION TACE with drug-eluting beads: Results from the PRECISION V randomized trial : B-240

Purpose: To evaluate the toxicity focussing on hepatic, gastrointestinal and cardiac parameters following PRECISION TACE with DC Bead? versus conventional transarterial chemoembolization (cTACE) in the treatment of intermediate-stage hepatocellular carcinoma (HCC). Methods and Materials: This prospective, randomized, multicentre study was conducted under best practice trial management and authorized by local institutional review boards. Informed consent was obtained. 212 patients (185 men/27 women; mean: 67 years) were randomized to be treated with DC Beads? or cTACE. The majority of both groups presented in a more advanced stage. Safety was measured by rate of adverse events (South West Oncology Group criteria) and changes in laboratory parameters. Cardiotoxicity was assessed by means of left ventricular ejection fraction (LVEF) in MRI or echocardiography. The results of the two groups were compared using the chi-square test and Student`s t-test. Results: Mean maximum alanine transaminase increase in the DC Bead group was 50% in the cTACE group (p < 0.001) and 59% for aspartate transaminase (p < 0.001). For bilirubin, mean increase was 5.30±15.13 vs. 13.53±73.89 µmol/L. Concerning gastrointestinal disorders, 120 adverse events (AEs) occurred in 57/93 (61.3%) patients in the DC Bead group vs. 114 in 49/108 (45.4%) in cTACE. Concerning hepatobiliary disorders, serious AEs occurred in 8/93 (8.6%) vs. 11/108 (10.2%) patients. LVEF showed an increase in the DC Bead group by +2.7±10.1 percentage points and a small decrease by -1.5±7.6 in the cTACE group, p=0.018. Conclusion: PRECISION TACE is safe, even in more advanced HCC patients. Serious liver and cardiac toxicity were significantly lower in the DC Bead group.

New wheat genotypes tolerant to aluminum toxicity obtained by mutation induction

Seed from the sensitive wheat (Triticum aestivumL.) cultivar Anahuac was treated to gamma-ray irradiation and eleven Al3+ tolerant mutants selected. The objective was to compare these mutants to the original Anahuac and to the tolerant wheat cultivars IAC-24 and IAC-60 from 1994 to 1996 in acid (Capão Bonito) and limed (Monte Alegre do Sul) soil field trials, in the State of São Paulo, Brazil. Grain yield and agronomic characteristics were analyzed. All the mutant lines yielded higher than the sensitive Anahuac cultivar in the acid soils of Capão Bonito. Under limed soil conditions, 10 mutants had a similar yield to the original sensitive cultivar and one a lower yield. The majority of the mutants were similar in yield to the tolerant cultivars IAC-24 and IAC-60 under both conditions. Some of the mutants showed altered agronomic characteristics, but these alterations did not generally influence the grain yield. The results indicated that tolerant lines with good characteristics may be obtained from a susceptible cultivar by mutation induction, thus allowing cropping under conditions where Al3 + is a limiting factor.

Quantification of fine root responses to selenium toxicity

Selostus: Seleenin myrkytysoireet juurissa

Toxicity of pymetrozine and thiamethoxam to Aphelinus gossypii and Delphastus pusillus

The objective of this work was to study the toxicity of pymetrozine and thiamethoxam to the cotton aphid parasitoid Aphelinus gossypii Timberlake and to the whitefly predator Delphastus pusillus (LeConte). Cotton leaves containing mummies of the parasitoid A. gossypii were collected and treated with seven concentrations of both insecticides. Parasitoid emergence was not affected by pymetrozine and ranged from 59.9% to 75.0%, but decreased with the increase of thiamethoxam concentrations ranging from 30.2% to 69.6%. Cotton leaves infested by whitefly and treated with recommended rates of both insecticides were collected three hours, three days and six days after spraying and colonized with larvae and adults of D. pusillus. Predators released on thiamethoxam-treated leaves experienced mortality from 70% to 100%, while those released on pymetrozine-treated leaves showed mortality from 0% to 20%. Topical toxicity from both insecticides was studied on larvae, pupae and adults of D. pusillus. The survival of predator after six days of exposure to 400, 600 and 800 mg/L of pymetrozine a.i. was higher than 69.6%, and to 25, 100 and 200 mg/L of thiamethoxam a.i. was lower than 8.7%. The toxicity data for A. gossypii and D. pusillus characterize the pymetrozine as harmless for both species, and thiamethoxam of low to moderate toxicity for A. gossypii treated mummies, and high toxicity for D. pusillus.

Acute toxicity of curative radiotherapy for intermediate- and high-risk localised prostate cancer in the EORTC trial 22991.

INTRODUCTION: This trial randomly assessed short-term adjuvant hormonal therapy added to radiotherapy (RT) for intermediate- and high-risk (UICC 1997 cT2a or cT1b-c with high PSA or Gleason score) localised prostate cancer. We report acute toxicity (CTCAE v2) assessed weekly during RT in relation to radiation parameters. PATIENTS AND METHODS: Centres selected the RT dose (70, 74 or 78Gy) and RT technique. Statistical significance is at 0.05. RESULTS: Of 791 patients, 652 received 3D-CRT (70Gy: 195, 74Gy: 376, 78Gy: 81) and 139 received IMRT (74Gy: 28, 78Gy: 111). During RT, grade 3 gastrointestinal (GI) and genitourinary (GU) toxicities were reported by 7 (0.8%) and 50 (6.3%) patients, respectively. No grade 4 was reported. The risk of grade 2 GI toxicity increased significantly with increasing D50%-rectum (p=0.004) and that of grade 2 GU toxicity correlated only to Dmax-bladder (p=0.051). 3D-RT technique, increasing total dose and V95% >400 cc increased D50% and Dmax. One month after RT, only 14 patients (1.8%) reported grade 3 toxicity. AST did not seem to influence the risk of GU or GI acute toxicity. CONCLUSION: RT up to 78Gy was well tolerated. Dmax-bladder and D50%-rectum influenced the risk of grade 2 GU toxicity and GI toxicity, respectively. Both were lower with IMRT but remained high for an irradiated RT volume>400 cc for 3D-RT and for a dose of 78Gy. Hormonal treatment did not influence acute toxicity.

On the retinal toxicity of intraocular glucocorticoids.

Corticosteroids are hormones involved in many physiological responses such as stress, immune modulation, protein catabolism and water homeostasis. The subfamily of glucocorticoids is used systemically in the treatment of inflammatory diseases or allergic reactions. In the eye, glucocorticoides are used to treat macular edema, inflammation and neovascularization. The most commonly used glucocorticoid is triamcinolone acetonide (TA). The pharmaceutical formulation of TA is not adapted for intravitreal administration but has been selected by ophthalmologists because its very low intraocular solubility provides sustained effect. Visual benefits of intraocular TA do not clearly correlate with morpho-anatomical improvements, suggesting potential toxicity. We therefore studied, non-common, but deleterious effects of glucocorticoids on the retina. We found that the intravitreal administration of TA is beneficial in the treatment of neovascularization because it triggers cell death of endothelial cells of neovessels by a caspase-independent mechanism. However, this treatment is toxic for the retina because it induces a non-apoptotic, caspase-independent cell death related to paraptosis, mostly in the retinal pigmented epithelium cells and the Müller cells.

Toxicity of neem oil to Bemisia tabaci biotype B nymphs reared on dry bean

The objective of this work was to determine the most susceptible nymphal stage of Bemisia tabaci biotype B to neem (Azadirachta indica A. Juss.) oil applied to dry bean (Phaseolus vulgaris L.) in a screenhouse. A solution of commercial oil (Dalneem) extracted from neem seeds was sprayed directly on each nymphal instar at 0, 0.1, 0.25, 0.5, 1 and 2% concentrations for lethal concentration (LC) determination, and at 0, 0.5 and 1% concentrations for lethal time (LT) determination. The number of living and dead nymphs was recorded five days after spraying for LC determination, and daily during six days for LT determination. The LC50 estimated for fourth instar nymphs occurred at 0.56% concentration. For all instars, LC50 and LC95 were estimated at 0.32 and 2.78% concentrations, respectively. The estimated values of LT50 at 1% concentration were 2.46, 4.45, 3.02 and 6.98 days for the first to fourth instars, respectively. The LT50 occurred at five days for 0.5% and at four days for 1% concentration in all instars. A mortality rate of over 80% was observed on the 6th day for the first to third instars at 1% concentration. The first three nymphal stages were more susceptible to neem oil when compared to the fourth nymphal stage.

Genesis of the Jurassic carbonate-hosted Pb-Zn deposits of Jebel Ressas (North-eastern Tunisia): Evidence from mineralogy, petrography and trace metal contents and isotope (O, C, S, Pb) geochemistry

The Jebel Ressas Pb-Zn deposits in North-Eastern Tunisia occur mainly as open-space fillings (lodes, tectonic breccia cements) in bioclastic limestones of the Upper Jurassic Ressas Formation and along the contact of this formation with Triassic rocks. The galena-sphalerite association and their alteration products (cerussite, hemimorphite, hydrozincite) are set within a calcite gangue. The Triassic rocks exhibit enrichments in trace metals, namely Pb, Co and Cd enrichment in clays and Pb, Zn, Cd, Co and Cr enrichment in carbonates, suggesting that the Triassic rocks have interacted with the ore-bearing fluids associated with the Jebel Ressas Pb-Zn deposits. The delta(18)O content of calcite associated with the Pb-Zn mineralization suggests that it is likely to have precipitated from a fluid that was in equilibrium with the Triassic dolostones. The delta(34)S values in galenas from the Pb-Zn deposits range from -1.5 to +11.4%, with an average of 5.9% and standard deviation of 3.9%. These data imply mixing of thermochemically-reduced heavy sulfur carried in geothermal- and fault-stress-driven deep-seated source fluid with bacterially-reduced light sulfur carried in topography-driven meteoric fluid. Lead isotope ratios in galenas from the Pb-Zn deposits are homogenous and indicate a single upper crustal source of base-metals for these deposits. Synthesis of the geochemical data with geological data suggests that the base-metal mineralization at Jebel Ressas was formed during the Serravallian-Tortonian (or Middle-Late Miocene) Alpine compressional tectonics.

MiR-SNPs as markers of toxicity and clinical outcome in Hodgkin Lymphoma patients

Background: In recent years, microRNA (miRNA) pathways have emerged as a crucial system for the regulation of tumorogenesis. miR-SNPs are a novel class of single nucleotide polymorphisms that can affect miRNA pathways. Design and Methods: We analyzed eight miR-SNPs by allelic discrimination in 141 patients with Hodgkin lymphoma and correlated the results with treatment-related toxicity, response, disease-free survival (DFS) and overall survival (OS). Results: The KRT81 (rs3660) GG genotype was associated with an increased risk of neurological toxicity (P=0.016), while patients with XPO5 (rs11077) AA or CC genotypes had a higher rate of bleomycin-associated pulmonary toxicity (P=0.048). Both miR-SNPs emerged as independent factors in the multivariate analysis. The XPO5 AA and CC genotypes were also associated with a lower response rate (P=0.036). XPO5 (P=0.039) and TRBP (rs784567) (P=0.022) genotypes emerged as prognostic markers for DFS, and XPO5 was also associated with OS (P=0.033). In the multivariate analysis, only XPO5 emerged as an independent prognostic factor for DFS (HR: 2.622; 95%CI 1.039-6.620; P=0.041). Given the influence of XPO5 and TRBP as individual markers, we then investigated the combined effect of these miR-SNPs. Patients with both the XPO5 AA/CC and TRBP TT/TC genotypes had the shortest DFS (P=0.008) and OS (P=0.008). Conclusion: miR-SNPs can add useful prognostic information on treatment-related toxicity and clinical outcome in Hodgkin lymphoma and can be used to identify patients likely to be chemoresistant or to relapse.