University of Extremadura

About: University of Extremadura is a education organization based out in Badajoz, Spain. It is known for research contribution in the topics: Population & Hyperspectral imaging. The organization has 7856 authors who have published 18299 publications receiving 396126 citations. The organization is also known as: Universidad de Extremadura.

Determination of main species involved in the first steps of TiO2 photocatalytic degradation of organics with the use of scavengers: The case of ofloxacin

Abstract: With the aid of different scavengers species involved in the first steps of TiO2/UVA (black light) photocatalytic elimination of ofloxacin (OFX) in water have been investigated. The effect of the presence of scavengers of hydroxyl radicals in bulk water (t-butanol), oxidant holes (h+) (2-propanol, iodide and oxalate), singlet oxygen (azide), electrons (oxygen) and superoxide ion radical (p-benzoquinone and tiron) has been checked at pH 7 with 0.03 M HClO4/ClO4− aerated media. The main elimination pathway leads to the formation of OFX + and takes place through an electronic transfer between the antibiotic and the catalyst surface. OFX + further reacts with O2 − leading to the reductive demethylation of OFX and generates 1 mole of hydrogen peroxide and ∼1 mole of formaldehyde per mole of OFX eliminated. The presence of phosphate promotes a change in the pathway degradation, possibly favoring the generation of HO radicals as well as the participation of this species on the oxidative demethylation of OFX and therefore reduces the production of H2O2. Therefore, OFX can be photocatalytically reduced and/or oxidized depending on the experimental conditions.

On Birkhoff orthogonality and isosceles orthogonality in normed linear spaces

Abstract: We survey mainly recent results on the two most important orthogonality types in normed linear spaces, namely on Birkhoff orthogonality and on isosceles (or James) orthogonality. We lay special emphasis on their fundamental properties, on their differences and connections, and on geometric results and problems inspired by the respective theoretical framework. At the beginning we also present other interesting types of orthogonality. This survey can also be taken as an update of existing related representations.

Distribution of two distinct Ca2+-ATPase-like proteins and their relationships to the agonist-sensitive calcium store in adrenal chromaffin cells.

Abstract: MANY cellular functions are regulated by activation of cell-surface receptors that mobilize calcium from internal stores sensitive to inositol 1,4,5-trisphosphate (Ins(l,4,5)P3) (ref. 1). The nature of these internal calcium stores and their localization in cells is not clear and has been a subject of debate. It was originally suggested2–5 that the Ins(l,4,5)P3-sensitive store is the endoplasmic reticulum, but a new organelle, the calciosome, identified by its possession of the calcium-binding protein, calsequestrin6, and a Ca2+-ATPase-like protein7 of relative molecular mass 100,000 (100K), has been described as a potential Ins(l,4,5)P3-sensitive calcium store. Direct evidence on whether the calciosome is the Ins(l,4,5)P3-sensitive store is lacking. Using monoclonal anti-bodies raised against the Ca2+-ATPase of skeletal muscle sarcoplasmic reticulum8, we show that bovine adrenal chromaffin cells contain two Ca2+-ATPase-like proteins with distinct subcellular distributions. A 100K Ca2+-ATPase-like protein is diffusely distributed, whereas a 140K Ca2+-ATPase-like protein is restricted to a region in close proximity to the nucleus. In addition, Ins(l,4,5)P3-generating agonists result in a highly localized rise in cytosolic calcium concentration ([Ca2+]i) initiated in a region close to the nucleus, whereas caffeine results in a rise in [Ca2+]i throughout the cytoplasm. Our results indicate that chromaffin cells possess two calcium stores with distinct Ca2+-ATPases and that the organelle with the 100K Ca2+-ATPase is not the Ins(l,4,5)P3-sensitive store.

Mechanisms Involved in Resveratrol‐Induced Apoptosis and Cell Cycle Arrest in Prostate Cancer—Derived Cell Lines

Abstract: Resveratrol is a polyphenol found at high concentrations in grapes and red wine with reported anticarcinogenic effects. We studied the molecular mechanism of resveratrol-induced apoptosis and proliferation arrest in prostate derived cells PZ-HPV-7 (nontumorigenic line), LNCaP (androgen-sensitive cancer line), and PC-3 (androgen-insensitive cancer line). Apoptosis and cell cycle distribution were evaluated by flow cytometry and proliferation by MTT assay and direct cell counting. Caspases, bax, bcl-2, cyclins, Cdks, p53, p21, and p27 were measured by Western blot and kinase activities of cyclin/Cdk complexes by immunoprecipitation followed by kinase assays with appropriate substrates. Resveratrol induced a decrease in proliferation rates and an increase in apoptosis in cancer cell lines in a dose- and time-dependent manner. These effects were coincident with cell accumulation at the G0/G1 phase. In LNCaP and PC-3, the apoptosis induced by resveratrol was mediated by activation of caspases 9 and 3 and a change in the ratio of bax/bcl-2. Expressions of cyclin D1, E, and Cdk4 as well as cyclin D1/Cdk4 kinase activity were reduced by resveratrol only in LNCaP cells. In contrast, cyclin B and Cdk1 expression and cyclin B/Cdk1 kinase activity were decreased in both cell lines in the presence of resveratrol. However, modulator proteins p53, p21, and p27 were increased by resveratrol only in LNCaP cells. These effects probably result in the observed proliferation arrest and disruption of cell cycle control. In addition, the specific differences found between LNCaP and PC-3 suggest that resveratrol acts through different mechanisms upon the androgen or estrogen receptor cell status.