Showing papers by "University of Alcalá published in 2005"

The Kuramoto model: A simple paradigm for synchronization phenomena

Abstract: Synchronization phenomena in large populations of interacting elements are the subject of intense research efforts in physical, biological, chemical, and social systems. A successful approach to the problem of synchronization consists of modeling each member of the population as a phase oscillator. In this review, synchronization is analyzed in one of the most representative models of coupled phase oscillators, the Kuramoto model. A rigorous mathematical treatment, specific numerical methods, and many variations and extensions of the original model that have appeared in the last few years are presented. Relevant applications of the model in different contexts are also included.

Biodegradation of lignocellulosics: microbial, chemical, and enzymatic aspects of the fungal attack of lignin.

Abstract: Wood is the main renewable material on Earth and is largely used as building material and in paper-pulp manufacturing. This review describes the composition of lignocellulosic materials, the different processes by which fungi are able to alter wood, including decay patterns caused by white, brown, and soft-rot fungi, and fungal staining of wood. The chemical, enzymatic, and molecular aspects of the fungal attack of lignin, which represents the key step in wood decay, are also discussed. Modern analytical techniques to investigate fungal degradation and modification of the lignin polymer are reviewed, as are the different oxidative enzymes (oxidoreductases) involved in lignin degradation. These include laccases, high redox potential ligninolytic peroxidases (lignin peroxidase, manganese peroxidase, and versatile peroxidase), and oxidases. Special emphasis is given to the reactions catalyzed, their synergistic action on lignin, and the structural bases for their unique catalytic properties. Broadening our knowledge of lignocellulose biodegradation processes should contribute to better control of wood-decaying fungi, as well as to the development of new biocatalysts of industrial interest based on these organisms and their enzymes. [Int Microbiol 2005; 8(3):195-204]

Body size in ecological networks

Abstract: Body size determines a host of species traits that can affect the structure and dynamics of food webs, and other ecological networks, across multiple scales of organization. Measuring body size provides a relatively simple means of encapsulating and condensing a large amount of the biological information embedded within an ecological network. Recently, important advances have been made by incorporating body size into theoretical models that explore food web stability, the patterning of energy fluxes, and responses to perturbations. Because metabolic constraints underpin body-size scaling relationships, metabolic theory offers a potentially useful new framework within which to develop novel models to describe the structure and functioning of ecological networks and to assess the probable consequences of biodiversity change.

History of the discovery and clinical introduction of chlorpromazine

Abstract: Background. The historical process of discovery and clinical introduction of chlorpromazine, one of the greatest advances of 20th century medicine and history of psychiatry, is analyzed.Methods. In this review, we have studied the original works of pioneers in the discovery and clinical use of chlorpromazine, as well as the contributions of prestigious researchers (historians, pharmacologists, psychiatrists, etc.) about this topic.Results. The discovery of phenothiazines, the first family of antipsychotic agents has its origin in the development of German dye industry, at the end of the 19th century (Graebe, Liebermann, Bernthsen). Up to 1940 they were employed as antiseptics, antihelminthics and antimalarials (Ehrlich, Schulemann, Gilman). Finally, in the context of research on antihistaminic substances in France after World War II (Bovet, Halpern, Ducrot) the chlorpromazine was synthesized at Rhone-Poulenc Laboratories (Charpentier, Courvoisier, Koetschet) in December 1950. Its introduction in anaesthes...

Sertraline treatment of pathological gambling: a pilot study.

Abstract: Objective Several open-label and double-blind studies have suggested that selective serotonin reuptake inhibitors may be useful in the treatment of pathological gambling. The purpose of this study was to evaluate the efficacy of sertraline in the treatment of pathological gambling. Method Sixty patients meeting the DSM-IV criteria for pathological gambling were treated for 6 months in a double-blind, flexible-dose, placebo-controlled study of sertraline 50 to 150 mg/day. Data were collected from November 1998 to January 2001. The primary outcome measure assessing change in clinical status was the responder rate with respect to the Criteria for Control of Pathological Gambling Questionnaire (CCPGQ). Secondary measures included the Clinical Global Impressions scale (CGI) (Severity of Illness and Improvement subscales), and Visual Analogue Scales assessing gambling frequency, severity, amount, and improvement. Concomitant medication and psychotherapy were not allowed during the study. Results At the end of the study, 23 sertraline-treated subjects (74%) and 21 placebo-treated subjects (72%) were considered as responders on the CCPGQ (p = .9). Similar results were obtained when the CGI-Improvement scale limited to symptoms of pathological gambling was used as an outcome measure. Sertraline was well tolerated throughout the study. Conclusion Sertraline was not statistically significantly superior to placebo in the overall sample. The power of the study was limited by the high placebo-response rate and the small sample size.

Soil health: a new challenge for microbiologists and chemists

Abstract: Soil health refers to the biological, chemical, and physical features of soil that are essential to long-term, sustainable agricultural productivity with minimal environmental impact. Thus, soil health provides an overall picture of soil functionality. Although it cannot be measured directly, soil health can be inferred by measuring specific soil properties (e.g. organic matter content) and by observing soil status (e.g. fertility). There is also increased interest in studying soil microorganisms in their particular environments, as microbial diversity is intimately related to soil structure and function. One of the key objectives in determining soil health is to acquire indicators that can be used to evaluate the soil’s current status and hence to develop sustainable agricultural systems. In this regard, significant progress has been made over the last few years in the development of specific biomarkers and macromolecular probes, enabling rapid and reliable measurements of soil microbial communities. In addition, modern molecular biological techniques, such as fluorescence in situ hybridization (FISH), reverse transcriptase polymerase chain reaction (RT-PCR), denaturing gradient gel electrophoresis (DGGE), and terminal restriction fragment length polymorphism (T-RFLP), have facilitated the analysis of microbial biodiversity and activity, whereas the application of modern analytical techniques, such as nuclear magnetic resonance (NMR) and pyrolysisgas chromatography-mass spectrometry (Py-GC-MS), have provided data on soil chemistry. The combination of these two approaches offers promise in determining soil health status. [Int Microbiol 2005; 8(1):13-21]

The history of barbiturates a century after their clinical introduction

Abstract: The present work offers an analysis of the historical development of the discovery and use of barbiturates in the field of psychiatry and neurology, a century after their clinical introduction. Beginning with the synthesis of malonylurea by von Baeyer in 1864, and up to the decline of barbiturate therapy in the 1960s, it describes the discovery of the sedative properties of barbital, by von Mering and Fischer (1903), the subsequent synthesis of phenobarbital by this same group (1911), and the gradual clinical incorporation of different barbiturates (butobarbital, amobarbital, secobarbital, pentobarbital, thiopental, etc). We describe the role played in therapy by barbiturates throughout their history: their traditional use as sedative and hypnotic agents, their use with schizophrenic patients in so-called "sleep cures" (Klaesi, Cloetta), the discovery of the antiepileptic properties of phenobarbital (Hauptmann) and their use in the treatment of epilepsy, and the introduction of thiobarbiturates in intravenous anesthesia (Lundy, Waters). We also analyze, from the historical perspective, the problems of safety (phenomena of dependence and death by overdose) which, accompanied by the introduction of a range of psychoactive drugs in the 1950s, brought an end to barbiturate use, except in specific applications, such as the induction of anesthesia and the treatment of certain types of epileptic crisis.

Molecular determinants of topoisomerase I poisoning by lamellarins: comparison with camptothecin and structure-activity relationships.

Abstract: A series of lamellarin derivatives have been studied as topoisomerase I (Top1) inhibitors. Molecular models of the ternary complexes formed between the DNA-Top1 ensemble and lamellarin D (LMD) or camptothecin (CPT) fully intercalated into the duplex DNA have been built and studied by means of nanosecond molecular dynamics simulations in aqueous solution. Our results show that the 20-OH and 8-OH of LMD can participate in hydrogen-bonding interactions with the side chains of Glu356 and Asn722, respectively, the latter being consistent with the finding that CEM/C2 cells, which are resistant to CPT, are cross-resistant to LMD. Our models also account for the observation that LMD stabilizes Top1 cleavage at CG sites in addition to the TG sites observed for CPT and rationalize the structure-activity relationships within the series. The deleterious effect of replacing the 20-OH in LMD with a hydrogen was confirmed using a set of thermodynamic integration free energy simulations.

Estimation of fuel moisture content by inversion of radiative transfer models to simulate equivalent water thickness and dry matter content: analysis at leaf and canopy level

Abstract: Fire danger models identify fuel moisture content (FMC) of live vegetation as a critical variable, since it affects fire ignition and propagation. FMC can be calculated by dividing equivalent water thickness (EWT) by dry matter content (DM). The "leaf optical properties spectra" (PROSPECT) model was inverted to estimate EWT and DM separately using the Leaf Optical Properties Experiment (LOPEX) database, based on 490 measurements of leaf optical and biochemical properties. DM estimations were poor when leaf samples were fresh (r/sup 2/ = 0.38). Results of a sensitivity analysis conducted on the spectral response of samples demonstrated that water absorption masks the effects of DM on the spectral response. This causes a poor estimation of FMC (r/sup 2/ = 0.33), even though EWT estimation was good (r/sup 2/ = 0.94). However, DM of dry samples was accurately estimated (r/sup 2/ = 0.84), since no water was present. FMC estimation in fresh leaf material improved considerably (r/sup 2/ = 0.89) by accounting for DM in fresh samples (r/sup 2/ = 0.71), when a constant species-dependent DM value is used. A similar approach was taken on a canopy level by linking the PROSPECT leaf model with the Lillesaeter infinitive reflectance canopy model using data from laboratory measurements under controlled conditions. As expected, results indicate grater difficulty to estimate DM and FMC on a canopy level, although similar trends were observed. DM estimation improved from r/sup 2/ = 0.12 to r/sup 2/ = 0.39 when considering measurements of dry samples, which when used for FMC estimation, correlations increase from r/sup 2/ = 0.62 to r/sup 2/ = 0.81. Therefore, DM can be accurately estimated only when plant material is dry, and it is a necessary measurement in order to estimate FMC accurately. DM remains stable over annual time periods although lower values are expected during the drought season. However, time variations in DM are smaller than DM variations among species. Because there is also a decrease in water content with low EWT values during phenologically dormant periods, multitemporal data could be used to estimate FMC. Further research must be applied on real canopies to confirm these results.

Energy, water and large-scale patterns of reptile and amphibian species richness in Europe

Abstract: We used regression analyses to examine the relationships between reptile and amphibian species richness in Europe and 11 environmental variables related to five hypotheses for geographical patterns of species richness: (1) productivity; (2) ambient energy; (3) water–energy balance, (4) habitat heterogeneity; and (5) climatic variability. For reptiles, annual potential evapotranspiration (PET), a measure of the amount of atmospheric energy, explained 71% of the variance, with variability in log elevation explaining an additional 6%. For amphibians, annual actual evapotranspiration (AET), a measure of the joint availability of energy and water in the environment, and the global vegetation index, an estimate of plant biomass generated through satellite remote sensing, both described similar proportions of the variance (61% and 60%, respectively) and had partially independent effects on richness as indicated by multiple regression. The two-factor environmental models successfully removed most of the statistically detectable spatial autocorrelation in the richness data of both groups. Our results are consistent with reptile and amphibian environmental requirements, where the former depend strongly on solar energy and the latter require both warmth and moisture for reproduction. We conclude that ambient energy explains the reptile richness pattern, whereas for amphibians a combination of water–energy balance and productivity best explain the pattern. © 2005 Elsevier SAS. All rights reserved.

Reproductive Size Thresholds in Tropical Trees: Variation among Individuals, Species and Forests

Abstract: Relative size at onset of maturity (RSOM) is defined as size at first reproduction divided by asymptotic maximal size. RSOM is remarkably constant among species within many higher clades of animals, but varies widely among tree species from the Pasoh Forest Reserve, Malaysia according to the work of S. C. Thomas. RSOM was examined for 16 mid-storey and canopy tree species from a second tropical forest at Barro Colorado Island (BCI), Panama. Interspecific variation in RSOM was equally large for BCI and Pasoh and was unrelated to gap dependence or life form for BCI species. The shape of the relationship between size and the proportion of individuals that were reproductive differed between forests, with an abrupt increase over a narrow range of sizes at Pasoh and a more gradual increase over a wider range of sizes at BCI. Both overtopping trees and heavy liana infestation reduced the probability that BCI trees were reproductive. This presumably reflects reduced availability of carbon for reproduction. We speculate that greater liana loads and a greater abundance of large, shade-casting trees at BCI may increase variation among individuals and contribute to the relatively wide range of sizes characterized by a mixture of sterile and fertile individuals observed for most BCI species.

Chloroplasts regulate leaf senescence: Delayed senescence in transgenic ndhF-defective tobacco

Abstract: Mitochondrial involvement has not been identified in the programmed cell death (PCD) of leaf senescence which suggests that processes such as those involving reactive oxygen species (ROS) are controlled by chloroplasts. We report that transgenic tobacco (DeltandhF), with the plastid ndhF gene knocked-out, shows low levels of the plastid Ndh complex, homologous to mitochondrial complex I, and more than a 30-day-delay in leaf senescence with respect to wt. The comparison of activities and protein levels and analyses of genetic and phenotypic traits of wtxDeltandhF crosses indicate that regulatory roles of mitochondria in animal PCD are assumed by chloroplasts in leaf senescence. The Ndh complex would increase the reduction level of electron transporters and the generation of ROS. Chloroplastic control of leaf senescence provides a nonclassical model of PCD and reveals an unexpected role of the plastid ndh genes that are present in most higher plants.

Clinical usefulness of polymorphonuclear elastase in predicting the severity of acute pancreatitis: Results of a multicentre study

Abstract: The usefulness and clinical applicability of quantitative plasma polymorphonuclear elastase determinations in the diagnosis of the severity of acute pancreatitis was analysed in a multicentre study and was compared with the usual prognostic systems of Ranson and Osborne et al. The study comprised 182 patients, 154 with a mild episode of acute pancreatitis and 28 with a severe episode, defined by the development of major complications or a fatal outcome. In the severe cases neutrophilic elastase reached significantly higher values than in mild cases (P less than 0.001) by the time the patient was admitted (2-12 h after the onset of the disease), reflecting considerable leucocyte activation. The sensitivity and specificity of this test are therefore greater than 90 per cent, with a positive severity predictive value of almost 80 per cent at the time of admission and 97 per cent after 24 h, and a negative predictive value of approximately 98 per cent. In addition to requiring 48 h for evaluation, the usual prognostic systems show a sensitivity of 77-85 per cent, a specificity of 70-77 per cent, a positive predictive value of 40-48 per cent, and a negative predictive value of 92-95 per cent, clearly lower than those obtained with leucocyte elastase. Polymorphonuclear elastase is therefore a very early and reliable marker in the diagnosis of the severity of acute pancreatitis, in addition to being easily adaptable to the routine of any hospital laboratory.

Editing of plastid RNA in Arabidopsis thaliana ecotypes.

Abstract: Post-transcriptional maturation of plastid-encoded mRNAs from land plants includes editing by making cytidine to uridine alterations at highly specific positions; this usually restores codon identities for conserved amino acids that are important for the proper function of the affected proteins. In contrast to the rather constant number of editing sites their location varies greatly, even between closely related taxa. Here, we experimentally determined the specific pattern of editing sites (the editotype) of the plastid genome of Arabidopsis thaliana ecotype Columbia (Col-0). Based on phylogenetic analyses of plastid open reading frames, we identified 28 editing sites. Two editing events in the genes matK and ndhB seem to have evolved late during the evolution of flowering plants. Strikingly, they are embedded in almost identical sequence elements and seem to be phylogenetically co-processed. This suggests that the two sites are recognized by the same trans-factor, which could help to explain the hitherto enigmatic gain of editing sites in evolution. In order to trace variations in editotype at the subspecies level we examined two other A. thaliana accessions, Cape Verde Islands (Cvi-0) and Wassilewskija (Ws-2), for the Col-0 editing sites. Both Cvi-0 and Ws-2 possess and process the whole set of editing sites as determined in Col-0, but the consequences of RNA editing differ at one position between the ecotypes.

Firm-provided training and temporary contracts

Abstract: This paper analyses the relationship between workers’ type of contract and the probability of receiving firm-provided training. In particular, we raise the following question: do workers with temporary contracts face the same probability of receiving training as workers with permanent contracts, once we account for the fact that both types of workers have different probabilities of being employed in a firm providing training? The results from our empirical analysis using data from the Spanish labour market suggest that workers with temporary contracts not only are less likely to be employed in training firms but, once they are in those firms, they also have a lower probability of being chosen to participate in firm-provided training activities.

Changes in the natural history of progressive multifocal leukoencephalopathy in HIV-negative lymphoproliferative disorders: impact of novel therapies.

Abstract: The aims of this study were to evaluate the clinical characteristics of HIV-negative patients affected by lymphoproliferative disorders (LPD) who developed progressive multifocal leukoencephalopathy (PML), to delineate the risk factors, and to analyze whether the new antineoplastic therapies are changing the natural history of this infectious disease. We retrospectively analyzed 46 cases with confirmed LPD-associated PML published from 1958 to 2004. Patients were stratified according to two different time periods: group A included patients diagnosed before 1989, and group B included patients diagnosed since 1990, after introduction of purine analogues. Group A patients (n = 22) had received alkylating agents and/or radiotherapy, and the majority (63.6%) had advanced Hodgkin disease. At univariate analysis, uncontrolled Hodgkin disease was the only risk factor for PML. In group B patients (n = 24), the most frequent treatments received were purine analogues (58.3%) and high-dose therapy with hematopoietic stem cell transplantation (33.3%; HDT/HSCT). B-cell chronic lymphocytic leukemia (45.8%) and aggressive non-Hodgkin lymphoma (24.9%) were the most frequent underlying LPDs. Patients treated with purine analogues were more likely to have active LPD, lower CD4 cell counts, and to be older and male than were HSCT recipients. The median interval from purine analogues or HDT/HSCT to PML was 11 months. In HDT/HSCT recipients, this interval was delayed for 10 months when peri-transplantation rituximab was used. Univariate analysis identified age >55 years, male sex, and CD4 cell counts £0.2 · 10 9 /L as risk factors for PML in patients treated with purine analogues. Mortality rates were 95.4% (group A patients), 90% (purine analogues), and 62.5% (HDT/HSCT recipients). At univariate analysis, the only factor that significantly correlated with recovery from infection was female sex. Our findings indicate (1) the possible reduction in reported cases associated with Hodgkin disease and the increasing number of published cases associated with the new antineoplastic therapies (purine analogues and HDT/ HSCT); (2) among patients treated with purine analogues, PML is more common in male patients with CD4 cell counts £0.2 · 10 9 /L; (3) the use of rituximab after HDT/ HSCT seems to delay the onset of PML; and (4) the prognosis is slightly better in transplant recipients. Am. J. Hematol. 80:271‐281, 2005. a 2005 Wiley-Liss, Inc.

Biological impacts of oil pollution and cleaning in the intertidal zone of exposed sandy beaches: Preliminary study of the “Prestige” oil spill

Abstract: On 13th September 2002, the oil tanker ‘‘Prestige’’ sunk off the Galician coast, causing one of the most important oil spills in history, which affected the entire coastline, particularly the exposed rocky shores and sandy beaches. Seventeen exposed sandy beaches were analysed along the Galician coast, in May 2003, and results were compared with previous data for September 1995 and 1996. The intertidal areas of the beaches were sampled in four tidal zones along the beach profile: swash, resurgence, retention and dry sand. Six cores of 0.05 m 2 were taken at each level and washed through a 1 mm mesh. Sediment samples were collected at each level for sediment analysis. The species were grouped into six main taxonomic groups: polychaetes, molluscs, marine crustaceans, semi-terrestrial crustaceans, insects and others. The total number of species was calculated in each group before and after the oil spill. The disturbance effect on each tidal level was determined. A decrease in the species richness was generally observed in all the studied beaches, although this decrease was not homogeneous in all the taxonomic groups. Polychaetes, insects, semi-terrestrial crustaceans and others lost species in all cases, while marine crustaceans did not show this tendency, losing species in some cases and gaining in others. The most affected beaches lost up to 66.7% of the total species richness after the oil spill. The most disturbed levels were swash, losing most of the polychaetes, and dry sand, with decrease in insects and semi-terrestrial crustaceans in many cases. Dry sand level received a high amount of oil and was more affected by grooming and cleaning activities where fuel and polluted material were removed, including algal wrack that is used by the supratidal macrofauna as food and shelter. 2005 Published by Elsevier Ltd.