Showing papers by "University of Oviedo published in 1991"
TL;DR: In this article, a modified boundary layer formulation based on the first two terms K and T, of the elastic field, is proposed for plane-strain elastic-plastic crack-tip fields.
Abstract: Plane-strain elastic-plastic crack-tip fields have been modeled with modified boundary layer formulations based on the first two terms K and T, of the elastic field. Geometries which maintain J-dominance are characterized by zero or positive T stresses, while geometries with negative T stresses can be described by a two-parameter characterization using J and T into full plasticity
633 citations
TL;DR: Long-term propranolol treatment significantly reduces the frequency of rebleeding from severe PHG, and may improve the prognosis of cirrhotic patients with this disorder.
247 citations
TL;DR: In this paper, the sequence of formation and propagation of structures, as well as the evolution of crustal thickening, in the Variscan belt of northwest Spain are proposed.
171 citations
TL;DR: In this article, the removal/recovery of copper, zinc and nickel ions in packed beds was studied, the variables considered being the influence of chemical treatment, particle size and metal concentration in the solutions percolated.
94 citations
TL;DR: Data indicated that all catchable and reproductive fish originated from indigenous populations and thus the policy of hatchery supplementation was a failure in these areas.
Abstract: A useful genetic marker exists through the apparent fixation of the LDH-5*100 allele in wild populations of brown trout in rivers from Asturias, Spain, contrasted with the near fixation of the LDH-5*90 allele in hatchery populations used to stock these rivers. In sampling locations where natural reproduction occurred, the *100 allele was found exclusively in all areas having no record of hatchery stocking. The *100 allele also predominated in three stocked areas having natural reproduction; in two of these areas a few individuals of the 0 + age class were homozygous for the *90 allele. These data indicated that all catchable and reproductive fish originated from indigenous populations and thus the policy of hatchery supplementation was a failure in these areas.
94 citations
86 citations
TL;DR: This article focused on the relationship between the processes of lexical retrieval and phonological encoding in sentence production and found that there is no clear evidence for a lexical bias effect on sublexical errors (segment movement and substitution).
Abstract: The present study focuses on the relationship between the processes of lexical retrieval and phonological encoding in sentence production. An analysis of spontaneous slips of the tongue in Spanish reveals that (1) there is as yet no clear evidence for a lexical bias effect on sublexical errors (segment movement and substitution), and hence for positive feedback from phonological encoding to the level of lexical representation; and (2) meaning and form appear to be largely dissociated in lexical errors, which lends support to the hypothesis that lexical retrieval proceeds in two independent stages during sentence production. These findings are discussed in the light of two alternative accounts of language production mechanisms: the interactive activation model and the structural, processing-stages model.
83 citations
TL;DR: Fosfomycin is taken into cells by active transport through the partially constitutive L-a-glycerophosphate uptake system (GlpT), as demonstrated by the finding that GlpT mutants are resistant to fosfomecin (Fo) and that constitutive mutants appear to be hypersusceptible to the drug.
Abstract: Fosfomycin [(-)-cis-1,2-epoxypropyl phosphonic acid] was discovered in 1968 as a secondary metabolite of several Streptomyces species (28). It aroused considerable interest, since it was a completely new molecule having antibacterial activity which exhibited relevant properties, such as a broad spectrum, covering many pathogenic and opportunistic gram-positive (Staphylococcus aureus and Streptococcus spp.) and gram-negative (Pseudomonas aeruginosa, Neisseria spp., and members of the family Enterobacteriaceae) bacteria (5, 19, 35, 43, 68). Furthermore, in combination with other antimicrobial agents, it was synergistic (17, 24, 50, 51, 61). Its chemical structure (Fig. 1) (12) presented new features, with a stable epoxide group and a direct carbonphosphorus bond, both of which were necessary for therapeutic activity (12, 34); these features explained the absence of cross-resistance with other antibiotics used in therapy (55). Fosfomycin, acting as a phosphoenolpyruvate analog, irreversibly inhibited phosphoenolpyruvate UDP-N-acetylglucosamine-3-O-enolpyruvyl transferase (enolpyruvyl transferase) (11, 34, 53, 54, 65), an enzyme which catalyzed the first step of peptidoglycan biosynthesis. It has almost no toxicity in humans (18, 28). It does not have an affinity for plasma proteins, in part explaining its lack of induction of allergic reactions (35, 55). Fosfomycin can be administered both parenterally (disodium salt) and orally (calcium, lysine and, more recently, trimethamine salts) (9, 10, 16, 21, 26) and shows excellent penetration into body fluids (15, 21, 52), with renal excretion of the active compound and short clearance times (9, 21, 35). Finally, it is taken up by eucaryotic cells and acts against intracellular parasites (29). Fosfomycin is taken into cells by active transport through the partially constitutive L-a-glycerophosphate uptake system (GlpT), as demonstrated by the finding that GlpT mutants are resistant to fosfomycin (Fo) and that constitutive mutants appear to be hypersusceptible to the drug (34). A secondary transport system, which mediates hexose phosphate uptake (Uhp), can be induced by glucose 6-phosphate. Under such conditions, transport of and susceptibility to fosfomycin by GlpTmutants became comparable to those of wild-type strains (34). Most chromosomally resistant mutants have an impairment in one or both of these uptake systems (33, 34, 60). Mutations that diminish the affinity of fosfomycin for its target enzyme also make cells resistant, although in this case there is a concomitant increase in the Km for phosphoenolpyruvate, resulting in a lower rate of synthesis of peptidoglycan (62). The use of fosfomycin has selected another type of resistant organisms which actively incorporate the drug (27, 37, 45) and have a fully sensitive enolpyruvyl transferase (38),
82 citations
TL;DR: Cystatin D, being the first described member of a third subfamily within the cystatin Family 2, thus appears to have a distinct function in the body in contrast to other cystatins.
79 citations
01 Jan 1991
TL;DR: The Iberian Peninsula consists of two very different parts: (1) the eastern half which constitutes the westernmost extension of the Alpine orogen; and (2) the western half (Iberian Massif) representing the southwesternmost and largest piece of the so-called European Hercynian Foldbelt as mentioned in this paper.
Abstract: The Iberian Peninsula consists of two very different parts: (1) the eastern half which constitutes the westernmost extension of the Alpine orogen; and (2) the western half (Iberian Massif) representing the southwesternmost and largest piece of the so-called European Hercynian Foldbelt. Although Precambrian and Paleozoic inliers are scattered within the former, they were generally so strongly reactivated during the Alpine orogeny that any attempt of correlation with the Iberian Massif has as yet failed. The latter, on the other hand, has been extensively surveyed in recent decades, and a summary of the present state of the art constitutes the main objective of this contribution. A tectonostra-tigraphic terrane analysis perspective is preferred for this purpose. This will allow a more accurate unravelling of each individual terrane evolutionary history, which will in turn greatly facilitate correlation.
78 citations
TL;DR: Both juvenile samples and scale analysis of anadromous salmon indicate that 2- year-old smolts were larger than 1-year-olds, which is at least, partially related to earlier migration of large fish, since sexual maturity of parr does not provide a complete explanation.
Abstract: Growth dynamics of juvenile Atlantic salmon, Salmo salar L., from two sections of the Narcea River and one of the Esva River (Northern Spain) were examined in relation to the development of bimodality in their size–frequency distributions. Size–bimodality was clearer under intermediate growth (section A) than under relatively fast or slow growth. The proportion of fish entering the upper modal group increase with growth intensity. Composition of upper and lower modal groups became fixed prior to December, and at this time both groups separated on the 90–95 mm interval. Fish exhibiting smolt appearance in late March (larger than 130 mm) had already been upper group fish in December, while parr-like fish and those that remained in the river by May (potential 2-year-old smolts) had formed the lower modal group. Anadromous salmon catch in the Narcea River was mostly of previously 1-year-old smolts (97.6%), of which 94% were larger than 100 mm by their first winter. In the Esva River, slow growth of juveniles is consistent with a large proportion of 2-year-old smolts (47.9%) among anadromous salmon. Both juvenile samples and scale analysis of anadromous salmon indicate that 2-year-old smolts were larger than 1-year-olds. Early disappearance of the former (before March) is, at least, partially related to earlier migration of large fish, since sexual maturity of parr does not provide a complete explanation. The Narcea stock have a minimum length at smolting of about 130 mm and an optimum smolt size in the 155–175 mm interval. Mean smolt length did not vary although the winter length changed between years.
TL;DR: It is concluded that a pericentric inversion in chromosome 4R, a reciprocal translocation between 3RL and 6RL, and a multiple translocation involving 4RL, 5RL, 6RS, and 7RS are present in rye relative to wheat.
Abstract: Cytological markers such as diagnostic C-bands, telocentrics, and translocations were used to identify the arms of rye chromosomes associated with wheat chromosomes at metaphase I in ph1b mutant wheat × rye hybrids. Arm homoeologies of rye chromosomes to wheat were established from the results of metaphase I pairing combined with available data on the chromosomal location of homoeoloci series in wheat and rye. Only arms 1RS, 1RL, 2RL, 3RS, and 5RS showed normal homoeologous relationships to wheat. The remaining arms of rye appeared to be involved in chromosome rearrangements that occurred during the evolution of the genus Secale. We conclude that a pericentric inversion in chromosome 4R, a reciprocal translocation between 3RL and 6RL, and a multiple translocation involving 4RL, 5RL, 6RS, and 7RS are present in rye relative to wheat.
TL;DR: The aminolysis of ethyl (±)-2-methylbutyrate with aliphatic amines is achieved using CC and PS lipases as catalysts and chiral amides are obtained in high-moderate enantiomeric excesses.
TL;DR: In vitro plant regeneration has been obtained from Capsicum annuum cvs.
Abstract: In vitro plant regeneration has been obtained from Capsicum annuum cvs. Pico and Piquillo. Shootbuds were induced from hypocotyl and cotyledon segments after 15–20 days of culture on MS basal medium supplemented with IAA and BAP or Zeatin. Shoot-buds grew into rosettes that rooted in MS plus NAA (0.1 mg/l) and IBA (0.05 mg/l) after 15 days. The small plantlets were successfully transferred to pots with a mixture of peat and perlite and maintained under greenhouse conditions. Elongation took place when the plantlets were growing in the greenhouse.
TL;DR: Only adults overwintered and no diapause was observed in any developmental stage and, therefore, the preadult stages are unlikely to overwinter and possible evolutionary steps in adaptation to cold regions are discussed.
Abstract: In temperate regions low temperatures seem to be the most restrictive factor for survival of Drosophila natural populations, which depends on the capacity of one or more developmental stages to resist unfavourable winter conditions. In this study we have attempted to answer the question of how D. melanogaster overwinters under natural temperature conditions. Only adults overwintered and no diapause was observed in any developmental stage. Thus, developmental duration becomes a decisive component with respect to overwintering potential and, therefore, the preadult stages are unlikely to overwinter. Possible evolutionary steps in adaptation to cold regions are discussed.
TL;DR: The results lead to the conclusion that in this system, porphyrin metabolism is controlled through hormonal regulation of 5-aminolevulinate synthase gene expression.
TL;DR: It is reported that OKA at concentrations as low as 0.5 nM produced neurotoxicity, characterized first by the desintegration of the neurites and swelling of cell bodies, and later by cellular death.
TL;DR: A comparative analysis in mammary tissues from women with different diseases revealed enhanced expression of Zn‐α2‐gp gene in benign breast lesions and a variable expression level in breast cancers.
TL;DR: Two napins (nIa and nIb), isolated from Brassica napus (rapeseed) seeds, have been sequenced and are considered representatives of a new distinct group of rapeseed napins since all the previously known napins exhibit 95% sequence similarity.
TL;DR: In this paper, a new enzymatic amperometric sensor for hydrogen peroxide based on a modified carbon paste electrode is described, which exhibits a relatively fast response time (42 s for 95% of the steady-state response) and yields currents linearly related to the hydrogen peroxidase concentration over the 10−7 to 10−5 mol/L range in both static and flow injection operations.
Abstract: A new enzymatic amperometric sensor for hydrogen peroxide based on a modified carbon paste electrode is described. Horseradish peroxidase and ferrocene mediator were immobilized by dissolution or dispersion in a graphite–paraffin oil paste. To prevent losses of immobilized chemicals under operational conditions, the electrode surface was coated with a Nafion membrane. The device exhibits a relatively fast response time (42 s for 95% of the steady-state response) and yields currents linearly related to the hydrogen peroxide concentration over the 10−7 to 10−5 mol/L range in both static and flow injection operations. The slope of the calibration plot remained constant for more than 20 days. Flow injection assays of hydrogen peroxide at a sampling rate of about 70 injections per hour, with a relative standard deviation of 1.4%, are possible. An easy and low cost preparation procedure is described.
TL;DR: In this article, a method for determining 2-furaldehyde (FUR) and 5-hydroxymethyl-2-furdehyde(HMF) in apple juices and juice concentrates was developed.
Abstract: A rapid and sensitive method for determining 2-furaldehyde (FUR) and 5-hydroxymethyl-2-furaldehyde (HMF) in apple juices and juice concentrates has been developed. The method for FUR and HMF involves the solid-liquid extraction of the juice by using a C-18 cartridge prior to reversed-phase separation with detection at 280 nm. The mobile phase was acetonitrile-water (8/92, v/v) at a flow rate of 1.0 ml/min. Recoveries from apple juices and juice concentrates spiked at different levels ranged from 94.1 to 104.0 (FUR) and 94.5 to 100.5 (HMF). The quantification limit for both, FUR and HMF, was 5 ppb.
TL;DR: In this article, the synthesis of novel σ-alkynyl cyclopentadienyl iron(II) complexes of the type [Fe(CCR)L 2 (η-C 5 H 5 )] is described.
TL;DR: The electrochemical behavior of the abuse drug cocaine has been studied in this article, where it was calculated that 2 electrons were involved, and the value obtained for the charge transfer coefficient was 0.362 ± 0.006.
Abstract: The electrochemical behavior of the abuse drug cocaine has been studied. Cocaine undergoes an irreversible oxidation process on carbon paste electrodes. It was calculated that 2 electrons were involved, and the value obtained for the charge transfer coefficient was 0.362 ± 0.006. Comparative voltammetric experiments yielded an estimated diffusion coefficient value for cocaine of 0.27 × 10−5 cm2 s−1. A linear calibration plot from 1.0 × 10−6 to 1.0 × 10−4M was obtained by using a scan rate of 50 mV s−1. A simple and reproducible procedure is proposed for the determination of cocaine in illegal dosage forms confiscated by police authorities; the results agree with those of a HPLC-UV method.
TL;DR: In this article, an electrochemical pretreatment regime was optimized for the determination of folic acid at cylindrical carbon fiber microelectrodes, which gave rise to higher faradaic and capacitive currents, presumably due to the presence of new surface functionalities.
TL;DR: The results indicate that, in S. clavuligerus, there is no obligatory relationship between the initiation of secondary metabolism and the stringent response, and cephalosporin biosynthesis was initiated during early exponential growth in complex media, without appreciable change in the small ppGpp pool.
Abstract: Summary: Cephalosporin biosynthetic activity and extracellular protease production increased during growth of Streptomyces clavuligerus in defined medium, while the level of guanosine 5′-diphosphate 3′-diphosphate (ppGpp) remained very low and stable. Cephalosporin biosynthesis (measured in resting cell systems) was initiated during early exponential growth in complex media, without appreciable change in the small ppGpp pool. Nutritional shift-down induced by withdrawal of Casamino acids caused a transient increase in ppGpp and a reduction of RNA accumulation. The increase in ppGpp was small in very young cultures, but increased as the culture aged. Twenty-seven spontaneous thiostrepton-resistant mutants were isolated and partially characterized. Most of them had a reduced ppGpp-forming ability and gave normal titres of cephalosporin. However, in complex medium, some mutants did not produce cephalosporins or extracellular protease, whereas others overproduced cephalosporins. The results indicate that, in S. clavuligerus, there is no obligatory relationship between the initiation of secondary metabolism and the stringent response.
TL;DR: Ch Chromosomal disruption of the APE2 gene completely abolishes the distinct activity band previously identified as aminopeptidase yscII, and a significant amino acid similarity was detected between the APe2 gene product and members of the zinc-dependent metallopePTidase gene family.
Abstract: Plasmids capable of complementing lap1, lap2 and lap3 mutations [R. J. Trumbly and G. Bradley (1983) J. Bacteriol. 156, 36–48] were isolated from a yeast YEp13 library by screening for activity against the chromogenic aminopeptidase substrate L-leucine β-naphthylamide in intact yeast colonies. The genomic inserts were shown to contain the structural genes for aminopeptidases yscII, yscIII and ysclIV. Plasmids containing the gene encoding aminopeptidase yscII of Saccharomyces cerevisiae, APE2 (LAP1) were analyzed in detail. APE2 was determined by DNA blot analysis to be a single-copy gene located on chromosome XI. The cloned fragment was used to idenify a 2.7-kb mRNA. The cloned APE2 gene was sequenced and found to consist of an open reading frame of 2583 bp encoding a protein of 861 amino acids. The protein sequence contains two putative N-glycosylation sites. A significant amino acid similarity was detected between the APE2 gene product and members of the zinc-dependent metallopeptidase gene family. Chromosomal disruption of the APE2 gene completely abolished the distinct activity band previously identified as aminopeptidase yscII [H. H. Hirsch, P. Suarez-Rendueles. T. Achstetter and D. ri. Wolf (1988) Eur. J. Biochem 173, 589–598] in crude extrats subjected to non-denaturing polyacrylamide gel electrophoresis and subsequent aminopeptidase activity staining. No vital consequence of aminopeptidase yscII absence on cell growth could be detected.
TL;DR: In this article, the components of the volatile fraction of coal tar pitch were studied by capillary gas chromatography and combined mass spectrometry using the OV-1701 stationary phase in both instances.
TL;DR: In this article, the authors analyse Noether's Second Theorem from a geometric viewpoint using the concepts of vector fields and forms along tangent bundle projections, and show that the second theorem can be analyzed from a geometrical viewpoint.
Abstract: We analyse Noether's Second Theorem from a geometric viewpoint using the concepts of vector fields and forms along tangent bundle projections.
TL;DR: The genotoxicity of acrolein in D. melanogaster was investigated using 2 different SMART assays, the eye spot and wing spot tests, and 2 germinal tests, the sex-linked recessive lethal (SLRLT) and sex chromosome loss (SCLT) tests, which indicate that ac rolein is mutagenic in the SLRLT when injected but not when fed.
Abstract: The genotoxicity of acrolein in D. melanogaster was investigated using 2 different SMART assays, the eye spot and wing spot tests, and 2 germinal tests, the sex-linked recessive lethal (SLRLT) and sex chromosome loss (SCLT) tests. For the 2 latter, exposure by feeding as well as injection was used. The results indicate that: (i) acrolein is mutagenic in the SLRLT when injected but not when fed; (ii) the SCLT did not reveal clastogenic effects; (iii) acrolein had genotoxic effects in both SMART assays; (iv) we also had several indications that acrolein is metabolized into a second genotoxic product.