Showing papers by "University of Córdoba (Spain) published in 2004"

The worldwide leaf economics spectrum

Abstract: Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

Grid-type metal ion architectures: functional metallosupramolecular arrays.

Abstract: Recent advances in supramolecular coordination chemistry allow access to transition-metal complexes of grid-type architecture comprising two-dimensional arrays of metal ions connecting a set of organic ligands in a perpendicular arrangement to generate a multiple wiring network. General design principles for these structures involve the thermodynamically driven synthesis of complex discrete objects from numerous molecular components in a single overall operation. Such supramolecular metal ion arrays combine the properties of their constituent metal ions and ligands, showing unique optical, electrochemical, and magnetic behavior. These features present potential relevance for nanotechnology, particularly in the area of supramolecular devices for information storage and processing. Thus, a dense organization of addressable units is represented by an extended "grid-of-grids" arrangement, formed by interaction of grid-type arrays with solid surfaces.

Developmental and Hormonally Regulated Messenger Ribonucleic Acid Expression of KiSS-1 and Its Putative Receptor, GPR54, in Rat Hypothalamus and Potent Luteinizing Hormone-Releasing Activity of KiSS-1 Peptide

Abstract: The gonadotropic axis is centrally controlled by a complex regulatory network of excitatory and inhibitory signals that is activated at puberty. Recently, loss of function mutations of the gene encoding G protein-coupled receptor 54 (GPR54), the putative receptor for the KiSS-1-derived peptide metastin, have been associated with lack of puberty onset and hypogonadotropic hypogonadism. Yet the pattern of expression and functional role of the KiSS-1/GPR54 system in the rat hypothalamus remain unexplored to date. In the present work, expression analyses of KiSS-1 and GPR54 genes were conducted in different physiological and experimental settings, and the effects of central administration of KiSS-1 peptide on LH release were assessed in vivo. Persistent expression of KiSS-1 and GPR54 mRNAs was detected in rat hypothalamus throughout postnatal development, with maximum expression levels at puberty in both male and female rats. Hypothalamic expression of KiSS-1 and GPR54 genes changed throughout the estrous cycle and was significantly increased after gonadectomy, a rise that was prevented by sex steroid replacement both in males and females. Moreover, hypothalamic expression of the KiSS-1 gene was sensitive to neonatal imprinting by estrogen. From a functional standpoint, intracerebroventricular administration of KiSS-1 peptide induced a dramatic increase in serum LH levels in prepubertal male and female rats as well as in adult animals. In conclusion, we provide novel evidence of the developmental and hormonally regulated expression of KiSS-1 and GPR54 mRNAs in rat hypothalamus and the ability of KiSS-1 peptide to potently stimulate LH secretion in vivo. Our current data support the contention that the hypothalamic KiSS-1/GPR54 system is a pivotal factor in central regulation of the gonadotropic axis at puberty and in adulthood.

Prospective, Randomized, Multicenter, Controlled Trial of a Bioartificial Liver in Treating Acute Liver Failure

Abstract: Objective: The HepatAssist liver support system is an extracorpo-real porcine hepatocyte-based bioartificial liver (BAL). The safety and efficacy of the BAL were evaluated in a prospective. random-ized, controlled, multicenter trial in patients with severe acute liver failure. Summary Background Data: In experimental animals with acute liver failure, we demonstrated beneficial effects of the BAL. Similarly, Phase I trials of the BAL in acute liver failure patients yielded promising results. Methods: A total of 171 patients (86 control and 85 BAL) were enrolled. Patients with fulminant/subfulminant hepatic failure and primary nonfunction following liver transplantation were included. Data were analyzed with and without accounting for the following confounding factors: liver transplantation, time to transplant, disease etiology, disease severity, and treatment site. Results: For the entire patient population, survival at 30 days was 71% for BAL versus 62% for control (P = 0.26). After exclusion of primary nonfunction patients, survival was 73% for BAL Versus 59% for control (it = 147; P= 0.12). When Survival was analyzed accounting for confounding factors. in the entire patient Population, there was no difference between the 2 groups (risk ratio = 0.67; P = 0.13). However, survival in fulminant/subfulminant hepatic failure patients was significantly higher in the BAL compared with the control group (risk ratio 0.56: P = 0.048). Conclusions: This is the first prospective, randomized, controlled trial of an extracorporeal liver support system, demonstrating safety and improved survival in patients with fulminant/subfulminant hepatic failure.

Advanced vaginal opening and precocious activation of the reproductive axis by KiSS-1 peptide, the endogenous ligand of GPR54

Abstract: The awakening of the gonadotrophic axis at puberty is the end-point of a complex cascade of sex developmental events that leads to the attainment of reproductive capacity. Recently, loss-of-function mutations of the gene encoding GPR54, the putative receptor for the KiSS-1-derived peptide metastin, have been linked to hypogonadotrophic hypogonadism, both in rodents and humans. However, the actual role of the KiSS-1/GPR54 system in the timing of puberty onset remains unexplored. We report herein that chronic central administration of KiSS-1 peptide to immature female rats induced the precocious activation of the gonadotrophic axis, as estimated by advanced vaginal opening, elevated uterus weight, and increased serum levels of luteinizing hormone (LH) and oestrogen. The central effect of KiSS-1 upon LH release appeared to be mediated via the hypothalamic LH-releasing hormone. In contrast, despite the well-documented permissive role of body fat stores and the adipocyte-derived hormone leptin in puberty maturation, acute activation of the gonadotrophic axis by KiSS-1 was persistently observed in pubertal animals under food deprivation, after central immunoneutralization of leptin, and in a model of leptin resistance. Overall, the present results, together with our recent data on maximum expression of KiSS-1 and GPR54 genes in the hypothalamus at puberty, provide novel evidence for a role of the KiSS-1 system as a downstream element in the hypothalamic network triggering the onset of puberty.

Optimization of alkali-catalyzed transesterification of Brassica carinata oil for biodiesel production

Abstract: Environmental concerns are driving industry to develop viable alternative fuels from renewable resources. On the other hand, to reduce food surplus, the Agricultural Policy of the European Union (EU) obliges the European farmers to leave a percentage of the arable land as set-aside, where can be grown, as an exception, vegetables for nonfood purposes, i.e., energetic ones. Currently, fossil fuels are used in diesel engines and are essential in industrialized places. In addition, petroleum-based diesel increases environmental pollution. To solve these problems, transesterified vegetable oil that has been grown in set-aside lands can be considered to be a renewable energy resource. In this sense, this work describes the optimization of the parameters involved in the transesterification process of Brassica carinata oil. Gas chromatography was used to determine the fatty acid composition of Brassica carinata oil and its esters. Results revealed that the free fatty acid content is a notorious parameter to dete...

Plant proteome analysis.

Abstract: Proteome analysis is becoming a powerful tool in the functional characterization of plants. Due to the availability of vast nucleotide sequence information and based on the progress achieved in sensitive and rapid protein identification by mass spectrometry, proteome approaches open up new perspectives to analyze the complex functions of model plants and crop species at different levels. In this review, an overview is given on proteome studies performed to analyze whole plants or specific tissues with particular emphasis on important physiological processes such as germination. The chapter on subcellular proteome analysis of plants focuses on the progress achieved for plastids and mitochondria but also mentions the difficulties associated with membrane-bound proteins of these organelles. Separate chapters are dedicated to the challenging analysis of woody plants and to the use of proteome approaches to investigate the interaction of plants with pathogens or with symbiotic organisms. Limitations of current techniques and recent conceptual and technological perspectives for plant proteomics are briefly discussed in the final chapter.

Nitrate reduction and the nitrogen cycle in archaea.

Abstract: The nitrogen cycle (N-cycle) in the biosphere, mainly driven by prokaryotes, involves different reductive or oxidative reactions used either for assimilatory purposes or in respiratory processes for energy conservation. As the N-cycle has important agricultural and environmental implications, bacterial nitrogen metabolism has become a major research topic in recent years. Archaea are able to perform different reductive pathways of the N-cycle, including both assimilatory processes, such as nitrate assimilation and N2 fixation, and dissimilatory reactions, such as nitrate respiration and denitrification. However, nitrogen metabolism is much less known in archaea than in bacteria. The availability of the complete genome sequences of several members of the eury- and crenarchaeota has enabled new approaches to the understanding of archaeal physiology and biochemistry, including metabolic reactions involving nitrogen compounds. Comparative studies reveal that significant differences exist in the structure and regulation of some enzymes involved in nitrogen metabolism in archaea, giving rise to important conclusions and new perspectives regarding the evolution, function and physiological relevance of the different N-cycle processes. This review discusses the advances that have been made in understanding nitrate reduction and other aspects of the inorganic nitrogen metabolism in archaea.

Chemical and Electrochemical Li-Insertion into the Li4Ti5O12 Spinel

Abstract: Lithium has been inserted into the spinel Li4Ti5O12 by both chemical and electrochemical methods. The cation distribution in the lithiated phases has been analyzed by 6,7Li NMR, Raman spectroscopy, and X-ray diffraction, and the distribution in the chemically inserted compound has been analyzed additionally by neutron diffraction. A refinement of structural parameters has been carried out by applying the Rietveld method to the neutron diffraction pattern. It is shown that the two insertion methods are based on different mechanisms. Chemically inserted lithium ions are trapped in the (48f) sites of the spinel structure from which they cannot be extracted by electrochemical means. In contrast to the electrochemical Li-insertion, which is accompanied by a spinel to rocksalt phase transition, no such structural change is found for chemical insertion. The consequences of the two different mechanisms for the reversibility of the insertion process are discussed.

Supercritical fluid extraction: a critical review of its analytical usefulness

Abstract: We examine the evolution of supercritical fluid extraction (SFE) since 1990 in order to pinpoint the reasons for its rare implementation by routine analytical laboratories despite its high analytical potential. We identify various reasons, and we propose ways to overcome the shortcomings behind them. We also discuss the great analytical potential of SFE and justify its use for routine work.

Expression of Ghrelin and its Functional Receptor, the Type 1a Growth Hormone Secretagogue Receptor, in Normal Human Testis and Testicular Tumors

Abstract: Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHS-R), has been primarily linked to the central neuroendocrine regulation of GH secretion and food intake, although additional peripheral actions of ghrelin have also been reported. In this context, the expression of ghrelin and its cognate receptor has been recently demonstrated in rat testis, suggesting a role for this molecule in the direct control of male gonadal function. However, whether this signaling system is present in human testis remains largely unexplored. In this study we report the expression and cellular location of ghrelin and its functional receptor, the type 1a GHS-R, in adult human testis. In addition, evaluation of ghrelin and GHS-R1a immunoreactivity in testicular tumors and dysgenetic tissue is presented. The expression of the mRNAs encoding ghrelin and GHS-R1a was demonstrated in human testis specimens by RT-PCR, followed by direct sequencing. In normal testis, ghrelin immunostaining was demonstrated in interstitial Leydig cells and, at lower intensity, in Sertoli cells within the seminiferous tubules. In contrast, ghrelin was not detected in germ cells at any stage of spermatogenesis. The cognate ghrelin receptor showed a wider pattern of cellular distribution, with detectable GHS-R1a protein in germ cells, mainly in pachytene spermatocytes, as well as in somatic Sertoli and Leydig cells. Ghrelin immunoreactivity was absent in poorly differentiated Leydig cell tumor, which retained the expression of GHS-R1a peptide. In contrast, highly differentiated Leydig cell tumors expressed both the ligand and the receptor. The expression of ghrelin and GHS-R1a was also detected in dysgenetic Sertoli cell-only seminiferous tubules, whereas germ cell tumors (seminoma and embryonal carcinoma) were negative for ghrelin and were weakly positive for GHS-R1a. In conclusion, our results demonstrate that ghrelin and the type 1a GHS-R are expressed in adult human testis and testicular tumors. Overall, the expression of ghrelin and its functional receptor in human and rat testis, with roughly similar patterns of cellular distribution, is highly suggestive of a conserved role for this newly discovered molecule in the regulation of mammalian testicular function.

Fusarium oxysporum as a Multihost Model for the Genetic Dissection of Fungal Virulence in Plants and Mammals

Abstract: Fungal pathogens cause disease in plant and animal hosts. The extent to which infection mechanisms are conserved between both classes of hosts is unknown. We present a dual plant-animal infection system based on a single strain of Fusarium oxysporum, the causal agent of vascular wilt disease in plants and an emerging opportunistic human pathogen. Injection of microconidia of a well-characterized tomato pathogenic isolate (isolate 4287) into the lateral tail vein of immunodepressed mice resulted in disseminated infection of multiple organs and death of the animals. Knockout mutants in genes encoding a mitogen-activated protein kinase, a pH response transcription factor, or a class V chitin synthase previously shown to be implicated in virulence on tomato plants were tested in the mouse model. The results indicate that some of these virulence factors play functionally distinct roles during the infection of tomato plants and mice. Thus, a single F. oxysporum strain can be used to study fungal virulence mechanisms in plant and mammalian pathogenesis.

Smoking and Parkinson's disease: systematic review of prospective studies.

Abstract: We estimated the pooled risk of tobacco smoking for Parkinson's disease (PD). Inclusion criteria included systematic searches of MedLine, PsycLIT, Embase, Current Contents, previously published reviews, examination of cited reference sources, and personal contact and discussion with several investigators expert in the field. Published prospective studies on PD and cigarette smoking. When two or more studies were based on an identical study, the study that principally investigated the relationship or the study that was published last was used. Seven prospective studies were carried out between 1959 and 1997, of which six reported risk estimates. Four cohorts were based on standardised mortality rates, which were exclusively of male. Only one study included risk estimates for both males and females separately. The risk of ever smoker was 0.51 (95% confidence interval, 0.43 to 0.61). There was an obvious protective effect of current smoking in the pooled estimate (relative risk, 0.35; 95% CI, 0.26-0.47). Former smokers had lower risk compared with never smokers (relative risk, 0.66; 95% CI, 0.49-0.88). Although our pooled estimates show that smoking is inversely associated with the risk of PD, the four prospective studies that were based on follow-up of mortality of smokers had many limitations. Further studies evaluating the association between smoking and PD in women are strongly needed.

Drought tolerance and transplanting performance of holm oak (Quercus ilex) seedlings after drought hardening in the nursery.

Abstract: Summary Drought stress is the main cause of mortality of holm oak (Quercus ilex L.) seedlings in forest plantations. We therefore assessed if drought hardening, applied in the nursery at the end of the growing season, enhanced the drought tolerance and transplanting performance of holm oak seedlings. Seedlings were subjected to three drought hardening intensities (low, moderate and severe) for 2.5 and 3.5 months, and compared with control seedlings. At the end of the hardening period, water relations, gas exchange and morphological attributes were determined, and survival and growth under mesic and xeric transplanting conditions were assessed. Drought hardening increased drought tolerance primarily by affecting physiological traits, with no effect on shoot/root ratio or specific leaf mass. Drought hardening reduced osmotic potential at saturation and at the turgor loss point, stomatal conductance, residual transpiration (RT) and new root growth capacity (RGC), but enhanced cell membrane stability. Among treated seedlings, the largest response occurred in seedlings subjected to moderate hardening. Severe hardening reduced shoot soluble sugar concentration and increased shoot starch concentration. Increasing the duration of hardening had no effect on water relations but reduced shoot mineral and starch concentrations. Variation in cell membrane stability, RT and RGC were negatively related to osmotic adjustment. Despite differences in drought tolerance, no differences in mortality and relative growth rate were observed between hardening treatments when the seedlings were transplanted under either mesic or xeric conditions.

Energy dependence of the Cronin effect from nonlinear QCD evolution.

Abstract: The nonlinear evolution of dense partonic systems has been suggested as a novel physics mechanism relevant for the dynamics of p-A and A-A collisions at collider energies. Here we study to what extent the description of Cronin enhancement in the framework of this nonlinear evolution is consistent with the recent observation in sqrt[s]=200 GeV d-Au collisions at the Relativistic Heavy Ion Collider. We solve the Balitsky-Kovchegov evolution equation numerically for several initial conditions encoding Cronin enhancement. We find that the properly normalized nuclear gluon distribution is suppressed at all momenta relative to that of a single nucleon. For the resulting spectrum of produced gluons in p-A and A-A collisions, the nonlinear QCD evolution is unable to generate a Cronin-type enhancement, and it quickly erases any such enhancement which may be present at lower energies.

Off-vine grape drying effect on volatile compounds and aromatic series in must from Pedro Ximénez grape variety.

Abstract: Changes in 36 volatile compounds of must from ripe grapes dried by direct exposure to sun and must from ripe grapes were studied. Compounds not dependent on sampling site in both musts were selected, and their concentration/Brix degree ratio values, were subjected to variance analysis. Only butan-1-ol and isoamyl alcohols showed no differences, while (E)-hex-3-en-1-ol, (Z)-hex-3-en-1-ol, (E)-hex-2-en-1-ol, (E)-hex-2-enal, hexanoic acid, isobutanol, benzyl alcohol, 2-phenylethanol, gamma-butyrolactone, gamma-hexalactone, and 5-methylfurfural, showed significant differences between the two must types, which may be ascribed to the drying process. An approach to describe must odor has been carried out by grouping volatile compounds in aromatic series, increasing their values in the fruity, solvent, sweet, and roasted series and diminishing the herbaceous as a consequence of the drying process.

Metallionen‐Gitterarchitekturen: funktionelle supramolekulare Metallkomplexe

Abstract: Jungste Entwicklungen auf dem Gebiet der supramolekularen Koordinationschemie haben Ubergangsmetallkomplexe mit Gitterstruktur ins Blickfeld der Forschung geruckt. Die Synthesen dieser komplexen molekularen Einheiten beruhen auf Selbstorganisationsprozessen, in denen die Zielverbindungen durch Koordination organischer Liganden an Metallionen in einer Stufe aus einer Vielzahl von Komponenten thermodynamisch gesteuert aufgebaut werden. Die organischen Liganden und die Metallionen bestimmen die photophysikalischen, elektrochemischen und magnetischen Eigenschaften der Gitterkomplexe, zusatzlich konnen jedoch auch “kollektive” Eigenschaften auftreten. Funktionelle Gitterkomplexe sind interessant fur die Nanotechnologie, z. B. hinsichtlich der Entwicklung einer (supra)molekularen Informationsspeicherung und -verarbeitung. Das Aufbringen dieser Komplexe auf Oberflachen fuhrt zu ausgedehnten matrixartigen Anordnungen von Metallionen mit bisher unerreichten Dichten adressierbarer Elemente.