Showing papers by "Autonomous University of Barcelona published in 1998"

Recombinant Humanized anti-HER2 Antibody (Herceptin) Enhances the Antitumor Activity of Paclitaxel and Doxorubicin Against HER2/neu Overexpressing Human Breast Cancer Xenografts

Abstract: Recombinant humanized anti-HER2 antibody, rhuMAb HER2, inhibits the growth of breast cancer cells overexpressing HER2 and has clinical activity. We explored in preclinical models its capacity to enhance the tumoricidal effects of paclitaxel and doxorubicin. In cultures of naturally HER2-overexpressing cancer cells, rhuMAb HER2 inhibited growth and enhanced the cytotoxic effects of paclitaxel. Treatment of well established BT-474 breast cancer xenografts overexpressing HER2 in athymic mice with rhuMAb HER2 resulted in a dose-dependent antitumor activity. In combination studies, treatment with paclitaxel and rhuMAb HER2 or doxorubicin and rhuMAb HER2 resulted in greater inhibition of growth than that observed with any agent alone. The combination of paclitaxel and rhuMAb HER2 resulted in the highest tumor growth inhibition and had a significantly superior complete tumor regression rate when compared with either paclitaxel or rhuMAb HER2 alone. Clinical trials that are built on these results are under way.

Climate warming, wildfire hazard, and wildfire occurrence in coastal eastern spain

Abstract: A climatic series (1941 to 1994) from a Mediterranean locality of NE Spain was used to calculate two wildfire hazard indices based on daily meteorological data. Both fire hazard indices increased over this period, as a consequence of increasing mean daily maximum temperature and decreasing minimum daily relative humidity. These trends were observed in both mean values of the indices and in the number of very high risk days. Annual data on the number of wildfires and burned area also show an increase from 1968 to 1994, and are significantly correlated with both fire hazard indices. Although other non-meteorological causes (e.g., human activities, fuel accumulation) have likely contributed to the observed increase of wildfires, an effect of climatic warming on wildfire occurrence is supported by this relationship.

The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome.

Abstract: The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last 10 years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathologic features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.

Aniline mineralization by AOP's: anodic oxidation, photocatalysis, electro-Fenton and photoelectro-Fenton processes

Abstract: The aniline degradation in acidic medium of pH≈3 under photocatalytic and electrochemical conditions has been investigated. The efficiency for substrate mineralization in each process has been comparatively analysed by the decrease in TOC of aniline solutions. Particular emphasis has been made on the role of Fe(II) ions and H 2 O 2 . The electrochemical experiments performed in the presence of both species (electro-Fenton conditions) leads to a fast aniline mineralization, which is notably increased by UVA irradiation (photoelectro-Fenton process). In photocatalysis with TiO 2 suspensions, the presence of H 2 O 2 and Fe(II) ions in solution notably increases the aniline degradation rate at the initial stages of the process, whereas the opposite effect occurs at long irradiation times. Benzoquinone, hydroquinone, nitrobenzene, phenol and 1,2,4-benzenetriol were detected as intermediates by HPLC in both, electrochemical and photocatalytic experiments. Short chain aliphatic acids, such as maleic and fumaric acids, were only found in the electrochemical experiments. Ammonium ions (75–80% of initial nitrogen) were generated in all solutions tested. A general reaction pathway that accounts for aniline mineralization to CO 2 involving those products is proposed.

Oxidative Stress at Onset and in Early Stages of Type 1 Diabetes in Children and Adolescents

Abstract: OBJECTIVE In diabetes, the persistence of hyperglycemia has been reported to cause increased production of oxygen free radicals through glucose autooxidation and nonenzymatic glycation. The aim of this study was to determine whether oxidative cellular damage occurs at the clinical onset of diabetes and in later stages of the disease in young patients. RESEARCH DESIGN AND METHODS Indicative parameters of lipoperoxidation, protein oxidation, and changes in the status of antioxidant defense systems were evaluated in single blood samples from 54 diabetic children, adolescents, and young adults and 60 healthy age- and sex-matched control subjects. RESULTS Malondialdehyde and protein carbonyl group levels in plasma were progressively higher in diabetic children and adolescents than in control subjects ( P < 0.0001). The highest erythrocyte superoxide dismutase (SOD) activity was found in diabetic children at onset of clinical diabetes. In diabetic adolescents, SOD was also significantly higher ( P < 0.0001) than in control subjects. Erythrocyte glutathione peroxidase was significantly lower in diabetic children and adolescents compared with control subjects ( P < 0.002). A significant decline in blood glutathione content at the recent onset of diabetes was found ( P < 0.0001). Furthermore, our results demonstrated progressive glutathione depletion during diabetes evolution. The plasma α-tocopherol/total lipids ratio and β-carotene levels during diabetes development ( P < 0.001) were low. CONCLUSIONS This cross-sectional study in young diabetic patients showed that systemic oxidative stress is present upon early onset of type 1 diabetes and is increased by early adulthood. Decreased antioxidant defenses may increase the susceptibility of diabetic patients to oxidative injury. Appropriate support for enhancing antioxidant supply in these young diabetic patients may help prevent clinical complications during the course of the disease.

High-field magnetoresistance at interfaces in manganese perovskites

Abstract: The low-field (LFMR) and high field (HFMR) magnetoresistance response of ceramic ${\mathrm{La}}_{2/3}{\mathrm{Sr}}_{1/3}{\mathrm{MnO}}_{3}$ (LSMO) samples having grain sizes diameters \ensuremath{\emptyset} ranging from 10 \ensuremath{\mu}m to 20 nm have been investigated. A limiting LFMR of about \ensuremath{\approx}30% is obtained for the \ensuremath{\emptyset} \ensuremath{\approx}0.5 \ensuremath{\mu}m but no larger values are obtained by further reduction of the grain size down to the nanometric range. On the contrary, the HFMR progressively rises when reducing the grain size. Magnetic and transport measurements suggest that HFMR originates from the existence of a noncollinear surface layer, having a thickness t that increases when reducing \ensuremath{\emptyset}. We have disclosed a clear relationship between the thickness, the intergranular resistance, and the height of the surface energy barrier. In addition, we show that in samples with submicronic grains, there is an intergranular Coulomb gap.

Critical thermal limits in Mediterranean ant species: trade‐off between mortality risk and foraging performance

Abstract: 1. In Mediterranean ant communities, a close relationship has been found between activity rhythm in the period of maximum activity and position in the dominance hierarchy: subordinate species are active during the day, when conditions are more severe, while dominants are active during the afternoon and the night. 2. Results obtained in this study confirmed that the species foraging at higher temperatures were closer to their critical thermal limits than the species foraging at lower temperatures. 3. This enabled two extreme strategies of foraging in relation to temperature to be distinguished: (1) heat-intolerant ant species behaved as risk-averse species, foraging at temperatures very far from their critical thermal limits; and (2) heat-tolerant ant species behaved as risk-prone species, foraging very near their critical thermal limits and running a high heat mortality risk. 4. Heat-tolerant species benefited from this strategy by having better foraging performance at high temperatures. 5. This wide range of thermal niches may be one reason why Mediterranean ant faunas are so diverse in the face of limited diversity in vegetation and habitat structure: the daily range of temperature may be sufficiently great to meet the requirement both of heat-adapted and cold-adapted species as well as a spectrum of intermediate forms.

A dysfunctional desmin mutation in a patient with severe generalized myopathy

Abstract: Mice lacking desmin produce muscle fibers with Z disks and normal sarcomeric organization. However, the muscles are mechanically fragile and degenerate upon repeated contractions. We report here a human patient with severe generalized myopathy and aberrant intrasarcoplasmic accumulation of desmin intermediate filaments. Muscle tissue from this patient lacks the wild-type desmin allele and has a desmin gene mutation encoding a 7-aa deletion within the coiled-coil segment of the protein. We show that recombinant desmin harboring this deletion cannot form proper desmin intermediate filament networks in cultured cells, nor is it able to assemble into 10-nm filaments in vitro. These findings provide direct evidence that a mutation in desmin can cause human myopathies.

Separative cancellation for projective modules over exchange rings

Abstract: A separative ring is one whose finitely generated projective modules satisfy the propertyA⊕A⋟A⊕B⋟B⊕B⇒A⋟B. This condition is shown to provide a key to a number of outstanding cancellation problems for finitely generated projective modules over exchange rings. It is shown that the class of separative exchange rings is very broad, and, notably, closed under extensions of ideals by factor rings. That is, if an exchange ringR has an idealI withI andR/I both separative, thenR is separative.

Lignotuber reserves support regrowth following clipping of two Mediterranean shrubs

Abstract: 1. We investigated whether reserves stored in the lignotubers of two Mediterranean shrubs, Arbutus unedo and Erica arborea, were significantly mobilized to support the demands of regrowth and respiration after clipping the tops at different frequencies. 2. After a single clipping, Arbutus showed a 29% decrease of phosphorus concentration by the end of the first growing season. Two years after recovery from clipping, the starch levels remained lower than those of unclipped plants. Similarly, Erica showed depletion of starch, but no nutrient reserves were depleted significantly. 3. Regrowth after multiple clippings mobilized a large fraction of the starch and nutrients stored in the lignotuber. Mean starch concentrations were depleted by 87–93% after multiple clippings and concentrations of nitrogen, phosphorus, potassium and magnesium were depleted by 10–45%, 27–41%, 19–39% and 23–31%, respectively. 4. An average-sized lignotuber produced 288 resprouts for Arbutus and 1990 resprouts for Erica during a 27 month period of multiple clippings, at the end of which the first plants died. 5. Plant mortality after multiple clipping was 10% for Arbutus and 30% for Erica, and was primarily attributed to exhaustion of carbon reserves because starch concentrations decreased by 96% in dead plants.

The role of competition by dominants and temperature in the foraging of subordinate species in Mediterranean ant communities.

Abstract: In this paper we test the influence of temperature and interference competition by dominant species on the foraging of subordinate species in Mediterranean ant communities. We have analyzed the changes in resource use by subordinate species in plots with different abundances of dominant ants, and in different periods of the day and the year, i.e., at different temperatures. The expected effects of competition by dominant species on foraging of subordinates were only detected for two species in the number of baits occupied per day, and for one species in the number of foragers at pitfall traps. In all three cases, subordinate species were less represented at baits or in traps in plots with a high density of dominants than in plots with a medium or low density of dominants. The number of workers per bait, and the foraging efficiency of subordinate species did not differ in plots differing in dominant abundance. Daily activity rhythms and curves of temperature versus foraging activity of subordinate species were also similar in plots with different abundance of dominant species, indicating no effect of dominants on the foraging times of subordinates. Instead, temperature had a considerable effect on the foraging of subordinate species. A significant relationship was found between maximum daily temperature and several variables related to foraging (the number of foragers at pitfall traps, the number of baits occupied per day, and the number of workers per bait) of a number subordinate species, both in summer and autumn. These results suggest that the foraging of subordinate ant species in open Mediterranean habitats is influenced more by temperature than by competition of dominants, although an effect of dominants on subordinates has been shown in a few cases. In ant communities living in these severe and variable environments, thermal tolerance reduces the importance of competition, and the mutual exclusion usually found between dominant and subordinate species appears to be the result of physiological specialization to different temperature ranges.

Single versus Double Proton-Transfer Reactions in Watson−Crick Base Pair Radical Cations. A Theoretical Study

Abstract: Single and double proton-transfer reactions in Watson−Crick Guanine−Cytosine (GC) and Adenine−Thymine (AT) radical cations have been studied using the hybrid density functional B3LYP method. Calibration calculations for the formamidine−formamide dimer, a model system of AT, have shown that B3LYP compares well to the high level ab initio correlated method CCSD(T), both for the neutral and cationic systems. The single proton-transfer reaction is favorable in both the GC and AT radical cations; it takes place from the ionized monomer (guanine and adenine, respectively), which increases its acidity, to the neutral fragment. For the two systems, GC and AT, the nonproton transferred and single proton transferred structures are almost degenerate (ΔE = 1.2 kcal/mol), and the process presents low energy barriers (4.3 kcal/mol for GC and 1.6 kcal/mol for AT). The double proton-transfer reaction is less favorable than the single one, in contrast to what is observed for the neutral systems. The relative stability of ...

Near-infrared spectroscopy in the pharmaceutical industry.

Abstract: Introduction Background and literature sources Specialized journals Internet addresses Previous reviews Fundamentals of the technique Principles of NIR spectroscopy NIR diffuse reflectance spectroscopy Operational procedures in the NIR Mathematical processing of signals Qualitative analysis Identification and qualification of raw materials and pharmaceutical preparations Determination of homogeneity Polymorphism and optical isomers Quantitative analysis Sample selection Multivariate calibration methods Determination of physical parameters Determination of moisture content Determination of active compounds and excipients Calibration transfer Miscellaneous applications Conclusions References

Aniline degradation by combined photocatalysis and ozonation

Abstract: The combination of TiO 2 -assisted photocatalysis and ozonation in the degradation of aniline in aqueous solution is investigated. From the experimental results obtained it is observed that the ozonation pretreatment followed by photocatalysis strongly increases the yield of TOC removal in comparison to either ozonation or photocatalysis carried out separately. The opposite sequence (photocatalysis pretreatment followed by ozonation) does not enhance the efficiency of aniline degradation. Nevertheless, the highest TOC removal was achieved by simultaneous ozonation and photocatalysis. A mechanism involving the formation of an ozonide anion radical previous to the generation of OH radicals is suggested to explain the synergic effect between ozone and TiO 2 under illumination.

Comparative field study of spring and summer leaf gas exchange and photobiology of the mediterranean trees Quercus ilex and Phillyrea latifolia

Abstract: Summer-induced changes in gas exchange, fluorescence and reflectance were measured on leaves of two co-occurring Mediterranean small trees, Quercus ilex and Phillyrea latifolia, in May, June and July 1996 in Central Catalonia (NE Spain). The humid 1996 summer only produced mild water stress conditions. However, photosynthesis (A) and stomatal conductance (g s ) decreased in June and July in both species. In June P. latifolia had higher net photosynthetic rates and lower stomatal conductances than Q. ilex, thus exhibiting higher instantaneous plant water use efficiencies. In agreement with these results, the photochemical reflectance index (PRI, calculated as (R 570 -R 531 )/(R 531 +R 570 )) of P. latifolia was lower, suggesting a possible lower xanthophyll de-epoxidation state. However, P. latifolia had lower ΔF/F' m and therefore a lower electron transport rate (ETR). The behaviour of PRI confirmed previous studies indicating a strong relationship between PRI, ΔF/F' m , and photosynthetic radiation-use efficiency (PRUE). PRI offers a simple, portable means of assessing PRUE with the potential for remote sensing applications. Finally, the possible ecological consequences of these results on the behaviour of the two species studied under the predicted warmer and drier conditions of global change are discussed.

Myrmecochorous dispersal distances: a world survey

Abstract: . Myrmecochorous dispersal distances are reviewed; the seed dispersal curve generated by ants shows a characteristic peak at short distances and a long tail, a shape suited to small densities of safe sites. Mean global distance is of 0.96 m (n= 2524) with a range of 0.01–77 m. Data have been broken down by geography (Northern hemisphere v. Southern hemisphere), taxonomy (ant subfamilies) and ecology (vegetation: sclerophyllous v. mesophyllous). Although a statistical difference exists between dispersal curves from the Northern hemisphere and the Southern hemisphere, this may be an artefact of lack of data from mesophyllous myrmecochores from this hemisphere. The four ant subfamilies do show also numerical differences but could not be subjected to statistical analysis. A difference between the shape of dispersal curve for sclerophyllous myrmecochores and mesophyllous myrmecochores has also been detected. We hypothesize that this difference is related to the myrmecological communities from both types of vegetation: dispersing ants from sclerophyllous vegetation would have smaller nest densities and/or bigger foraging areas than dispersing ants from mesic environments.

Mediterranean terrestrial ecosystems: research priorities on global change effects

Abstract: Ecosystems of the Mediterranean Basin are suggested as model regions for global change research, particularly in relation to the importance of land use changes. The large body of preexisting ecological knowledge should facilitate progress on complex issues relating to interactions among multiple drivers of global change, including climate, atmospheric, land use and socio-economic changes. Four research areas appear as priorities in relation to pressing needs for prediction: (1) fire regimes and effects; (2) feedbacks from the land to the atmosphere; (3) water availability and quality; and (4) changes in ecological diversity. We summarize current knowledge and present future directions for research in these areas. While a number of the topics outlined as priorities are presently addressed by ongoing studies, some of the future challenges will lie in appropriate coordination and synthesis of that research. We suggest that this structuring effort could serve as an example to be applied in other MTEs and across MTEs.

Transcription of a Broad Range of Self-Antigens in Human Thymus Suggests a Role for Central Mechanisms in Tolerance Toward Peripheral Antigens

Abstract: The role of the thymus in the induction of tolerance to peripheral antigens is not yet well defined. One impending question involves how the thymus can acquire the diversity of peripheral nonthymic self-Ags for the process of negative selection. To investigate whether peripheral Ags are synthesized in the thymus itself, we have determined the expression of a panel of circulating and cell-bound peripheral Ags, some of which are targets of autoimmune diseases, at the mRNA level in total thymic tissue and in its main cellular fractions. Normalized and calibrated RT-PCR experiments demonstrated the presence of transcripts of nonthymic self-Ags in human thymi from 8 days to 13-yr-old donors. Out of 12 glands, albumin transcripts were found in 12; insulin, glucagon, thyroid peroxidase, and glutamic acid decarboxylase (GAD)-67 in six, thyroglobulin in five, myelin basic protein and retinal S Ag in three, and GAD-65 in one. The levels of peripheral Ag transcripts detected were age-related but also showed marked interindividual differences. Cytokeratin-positive stromal epithelial cells, which are a likely cellular source for these, contained up to 200 transcript copies of the most expressed peripheral Ags per cell. These results implicate the human thymus in the expression of wide representation of peripheral self-Ags and support the view that the thymus is involved in the establishment of tolerance to peripheral Ags. The existence of such central mechanism of tolerance is crucial for the understanding of organ-specific autoimmune diseases.