Search results for "OPOS"

Atmospheric protein chemistry influenced by anthropogenic air pollutants: nitration and oligomerization upon exposure to ozone and nitrogen dioxide

2017

The allergenic potential of airborne proteins may be enhanced via post-translational modification induced by air pollutants like ozone (O3) and nitrogen dioxide (NO2). The molecular mechanisms and kinetics of the chemical modifications that enhance the allergenicity of proteins, however, are still not fully understood. Here, protein tyrosine nitration and oligomerization upon simultaneous exposure of O3 and NO2 were studied in coated-wall flow-tube and bulk solution experiments under varying atmospherically relevant conditions (5–200 ppb O3, 5–200 ppb NO2, 45–96% RH), using bovine serum albumin as a model protein. Generally, more tyrosine residues were found to react via the nitration pathw…

Los pasados políticos de Grass / Ridruejo

2006

On Conditioning Operators

1999

The construction of conditional events (so-called measure-free conditioning) has a long history and is one of the fundamental problems in non-deterministic system theory (cf. [6]). In particular, the iteration of measure-free conditioning is still an open problem. The present paper tries to make a contribution to this question. In particular, we give an axiomatic introduction of conditioning operators which act as binary operations on the universe of events. The corresponding axiom system of this type of operators focus special attention on the intuitive understanding that the event ‘α given β’ is somewhere in “between” ‘α and β’ and ‘β implies α’. A detailed motivation of these axioms can …

Lawvere–Tierney sheaves in Algebraic Set Theory

2009

We present a solution to the problem of defining a counterpart in Algebraic Set Theory of the construction of internal sheaves in Topos Theory. Our approach is general in that we consider sheaves as determined by Lawvere-Tierney coverages, rather than by Grothendieck coverages, and assume only a weakening of the axioms for small maps originally introduced by Joyal and Moerdijk, thus subsuming the existing topos-theoretic results.

La agricultura en el País Valenciano entre el VI y el I milenio a.C.

2013

El trabajo es un intento de definir el funcionamiento de la agricultura desde la llegada de los primeros agricultores a mediados del VI milenio cal BC, hasta el fin del mundo Ibérico a inicios del s II a.C. La base es fundamentalmente el registro carpológico recuperado en 29 yacimientos, que permite conocer cuáles son las especies recolectadas y cultivadas en cada una de las fases, así como intentar una aproximación a las formas de cultivo. Para ello recurrimos a otros elementos como son las herramientas con las que cuentan los agricultores y el registro faunístico, con la intención de determinar si estos últimos están siendo utilizados como fuerza de trabajo, fundamentalmente para tirar de…

The temnospondyl amphibian Cyclotosaurus from the Upper Triassic of Poland

2005

A gap in the Late Triassic fossil record of the capitosaur amphibian Cyclotosaurus is filled by new material from lacustrine deposits at Krasiejow, Poland, corresponding in age to the Lehrberg Beds (late Carnian) of Germany. The skull of the Polish cyclotosaur is intermediate in several respects between that of Cyclotosaurus robustus from the middle Carnian Schilfsandstein of Germany and the younger C. mordax from the early Norian Stubensandstein. It shows a decrease in the width of the skull and in the degree of con- cavity of the posterior margin of the skull roof. The differ- ences are significant enough to warrant erection of a novel species, the name Cyclotosaurus intermedius sp. nov. …

Induction of apoptosis in human retinoblastoma cells by topoisomerase inhibitors

1998

PURPOSE:To examine the apoptotic effect induced in human retinoblastoma Y79 cells by camptothecin, etoposide, and amsacrine, to examine the effect of these drugs on the expression of many apoptosis-related modulators, and to test the antiapoptotic effect exerted by insulin-like growth factor-I (IGF-I). METHODS:Morphologic features of apoptosis were demonstrated using acridine orange- ethidium bromide staining and electron microscopy. DNA fragmentation was determined by means of an in situ cell detection procedure (TdT-dUTP terminal nick-end labeling [TUNEL]) or by electrophoresis on agarose gels and was quantified by enzyme-linked immunosorbent assay. The expression of apoptosis-related mod…

Apoptotic effects of different drugs on cultured retinoblastoma Y79 cells

1998

This paper deals with the apoptotic effect exerted in human retinoblastoma Y79 cells by a number of compounds. A remarkable effect was observed after treatment with DNA-damaging agents, such as camptothecin, etoposide, cisplatin and carboplatin; camptothecin was found to be the most efficacious. Treatment with these compounds induced the appearance of morphological features of apoptosis in the cells together with the distinct fragmentation of DNA, as shown by agarose gel electrophoresis. These effects were also accompanied by a remarkable increase in the level of p53. Many other compounds, which are not DNA-damaging agents, induced the morphological features of apoptosis but none of them we…

Diffusion technique for the generation of gaseous halogen standards

2009

Abstract Halogens are known to play an important role in the tropospheric ozone-depletion chemistry and are of special interest because of their influence on the atmospheric oxidation capacity. In this paper, we investigate the application of a capillary diffusion technique for the generation of gaseous halogen standards like Br 2 , IBr, ICl and I 2 . The influence of capillary dimension (i.e. length and inner diameter), ambient pressure and headspace volume of the diffusion vessel on the test gas output has been evaluated. The experimental output rates are determined from the mass loss of the analyte vessel on a regular schedule and compared with their respective theoretical predictions. W…

Resistance of p53 knockout cells to doxorubicin is related to reduced formation of DNA strand breaks rather than impaired apoptotic signaling

2003

The anthracycline doxorubicin (adriamycin) is an important chemotherapeutic agent used in the treatment of solid epithelial and mesenchymal tumors as well as leukemias. A variety of mechanisms has been proposed to be involved in doxorubicin-induced cytotoxicity such as DNA intercalation, oxidative stress, DNA strand breakage by inhibition of topoisomerase II, activation of death receptors, and altered p53 expression. Concerning doxorubicin resistance and p53 status data reported are contradictory. Here, we show that mouse fibroblasts deficient in p53 (p53(-/-)) are more resistant to doxorubicin than p53 wild-type (p53 wt) cells. This is in contrast to other genotoxic agents (UV-light, alkyl…