Showing papers by "University of Alcalá published in 1996"

Mechanisms of touch-evoked pain (allodynia): a new model

Abstract: In this paper we review the current neurophysiological models of touch-evoked pain and present a new proposal that addresses the mechanisms of allodynia. The new model is based on the notion that A-β mechanoreceptors can gain access to nociceptive neurones by means of a presynaptic link, at central level, between low threshold mechanoreceptors and nociceptors. We propose that the excitation of nociceptors provoked by a peripheral injury activates the spinal interneurones that mediate primary afferent depolarization (PAD) between low threshold mechanoreceptors and nociceptors. As a consequence of the increased and persistent barrage driving these neurones their excitability is increased such that, when activated by low threshold mechanoreceptors from areas surrounding the injury site, they produce a very intense PAD in the nociceptive afferents which is capable of generating spike activity. This activation would be conducted antidromically in the form of dorsal root reflexes (DRRs) but would also be conducted forward activating the second order neurones normally driven by nociceptors. The sensory consequence of this mechanism is pain evoked by the activation of low threshold mechanoreceptors from an area surrounding an injury site (allodynia).

Colonization and infection with methicillin-resistant Staphylococcus aureus: associated factors and eradication.

Abstract: Objectives To identify characteristics associated with methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection, and to evaluate the efficacy of systemic and topical antimicrobials in the eradication of MRSA carriage among hospitalized patients. Design A case-control study was done to identify associations. Odds ratios were estimated by unconditional multiple logistic regression. Cohort study was done to evaluate MRSA decolonization efficacy by an oral regimen. Patients infected or colonized with MRSA received a 5-day course of oral (160 mg/800 mg) trimethoprim-sulfametroxazole twice daily and 600 mg of rifampin once daily as decolonization treatment. The proportion of MRSA-free patients after decolonization treatment was determined. Persistence of clearing was estimated by the Kaplan-Meier method. Setting Ramon y Cajal Hospital, a 1,249-bed, tertiary-care teaching hospital in Madrid, Spain. Patients One hundred ninety-two patients with hospital-acquired MRSA infection/colonization and 195 MRSA-free random controls. Results Six factors were associated independently with MRSA infection/colonization: age (every 10 years of age, odds ratio [OR] = 1.3); ward (surgical, OR = 1; medical, OR = 3.1; intensive care unit, OR = 60); previous hospitalization (OR = 6.9); coma (OR = 25.3); invasive procedures (each, OR = 1.7); 3 or more weeks of hospitalization (OR = 3.8). We failed to show antibiotic therapy to be an independent risk factor for MRSA hospital infection/colonization. Overall, MRSA eradication was 64.2% by day 2 to 9 after completion of treatment. Kaplan-Meier product limit survival analysis showed that the probability of remaining MRSA-free was 65.3% (SE = 0.09) at 32 days after completion of treatment. Conclusions The results offer a rationale for reduction of MRSA infection/colonization in the hospital by interventions aimed at early identification of patients at higher risk, at prompt discharge of patients, and at preventing dissemination while performing invasive procedures. They also provide estimates of antibiotic treatment efficacy to reduce the reservoir of MRSA in the hospital.

Mapping the spatial distribution of forest fire danger using GIS

Abstract: A geographical information system (GIS) is proposed as a suitable tool for mapping the spatial distribution of forest fire danger. Using a region severely affected by forest fires in Central Spain as the study area, topography, meteorological data, fuel models and human-caused risk were mapped and incorporated within a GIS. Three danger maps were generated: probability of ignition, fuel hazard and human risk, and all of them were overlaid in an integrated fire danger map, based upon the criteria established by the Spanish Forest Service. GIS make it possible to improve our knowledge of the geographical distribution of fire danger, which is crucial for suppression planning (particularly when hotshot crews are involved) and for elaborating regional fire defence plans.

The Behavior of Paracetamol in Mixtures of Amphirotic and Amphiprotic-Aprotic Solvents. Relationship of Solubility Curves to Specific and Nonspecific Interactions

Abstract: The solubility of paracetamol was studied at 25°C in mixtures of amphiprotic and aprotic solvents of varying polarity (ethyl acetate-ethanol, ethanol-water, dioxane-water). A plot of the solubility mole fraction of the drug versus the solubility parameter of the solvent mixtures reached a peak in dioxane-water, and two solubility maxima within the polarity range provided by the ethanol-water and ethanol-ethyl acetate mixtures. This "chameleonic effect" can be quantitatively described in terms of cavity formation, nonspecific and specific interactions, represented by the Hildebrand solubility parameter and the acidic and basic solubility parameters of the solvent mixtures. The model predicts two solubility maxima, as found experimentally. The behavior of paracetamol in dioxane-water mixtures is similar to that of other drugs, showing a single maximum, although a small peak and a valley are also observed near the solubility parameter region where the maximum in ethanol-water appears. An increase in the temperature of fusion of the solid phase by about eight degrees was observed after equilibration of the powder with ethanol, ethyl acetate and dioxane. No changes in the solid phase were observed in water and aqueous mixtures below 50% water. The same change in the solid phase was also found in ethanol-ethyl acetate mixtures; it was independent of the nature and cosolvent ratio and had little effect on the relative variation of solubility with solvent composition. The solid phase contributes as a constant to the total solubility.

A comparative analysis of the genetic relationships between rye cultivars using RFLP and RAPD markers

Abstract: The genetic similarities of eight closely related rye cultivars were estimated using two molecular marking techniques: restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD). Cultivars were evaluated for variation by 11 random cDNA and genomic clones used in combination with four restriction enzymes and 40 decamer primers. A total of 53 polymorphic RFLP fragments and 94 polymorphic RAPD fragments were observed. Based on the presence/absence of fragments, two genetic similarity matrices were calculated which were then used in cluster analysis. Differences between pair of cultivars were observed in RFLP and RAPD dendrograms. RFLP analysis produced estimates of genetic relationships more in accordance with the partially known pedigree of the cultivars than did RAPD analysis. The use of bulk samples of DNA in these analyses affected the sensitivity of RAPD assays more strongly. Dendrograms which took into account all fragments produced, either by RFLP or RAPD, reflected better the relationships between cultivars than did dendrograms based on only one type of marker. This reflects the importance of the number of markers used in determining the genetic relationships between genotypes.

Rheological Properties of the L Phase and the Hexagonal, Lamellar, and Cubic Liquid Crystals of the CTAB/Benzyl Alcohol/Water System

Abstract: The rheological properties of different phases of the CTAB/benzyl alcohol/water system have been studied. The L phase, except the samples close to the hexagonal liquid crystal, is a viscous fluid with a characteristic Newtonian behavior. On the contrary, the L phase samples close to the hexagonal phase are pseudoplastic fluids built up of cylindrical micelles with elastic properties. The hexagonal liquid crystal behaves as a shear thinning fluid with a well-defined zero-shear-rate viscosity, while the lamellar liquid crystal does not show a zero-shear-rate viscosity and it presents yield stress values. Both liquid crystals have significant elastic properties although we could not find any linear region of viscoelasticity in the lamellar phase. The cubic liquid crystal is also an elastic phase with ringing gel properties. The hexagonal and cubic liquid crystals follow the Maxwell treatment only at low angular frequencies. Consequently, from the results the relaxation time and the instantaneous elastic modu...

Comparison of a new type of polytetrafluoroethylene patch (Mycro Mesh) and polypropylene prosthesis (Marlex) for repair of abdominal wall defects.

Abstract: BACKGROUND Two types of prosthetic material used for repairing hernial defects of the abdominal wall were compared: Mycro Mesh and Marlex. Mycro Mesh (MM) is a new polytetrafluoroethylene product of layered, microporous structure. Macroscopically, it presents regularly distributed, 2-mm orifices that perforate the biomaterial. Marlex (PL) is a well-known polypropylene mesh product with a macroporous structure. STUDY DESIGN In 24 white New Zealand rabbits, a full-thickness (except skin) 5 x 7-cm defect was created in the anterior wall of the abdomen. Defects were repaired with either MM (n = 12) or PL (n = 12) implants and studied at 14, 30, 60, and 90 days after implantation. Samples of the interfaces between prosthesis and subcutaneous tissue, visceral peritoneum, and receptor tissue, respectively, were studied. Samples were processed for optical microscopy and scanning electron microscopy (SEM). An immunohistochemical study was made using RAM-11, a monoclonal antibody specific for rabbit macrophages. The tensile strength of the repairs was made using an Instron tensiometer on 2-cm wide transversal strips that included the prosthesis and its anchor zones to the receptor tissue. RESULTS The formation of adhesions between the prosthesis and intestine was important with the PL implants but not with the MM implants. Optical microscopy and SEM showed formation of an organized connective tissue surrounding the MM implants. At 90 days, compact bridges of connective tissue linked the tissue on the subcutaneous and peritoneal sides of the prosthesis. The PL implants became integrated into a disorganized, highly vascularized connective tissue. The intensity of the macrophage response was similar in both prostheses and decreased between days 14 and 90 (Student-Newman-Keuls test p = 0.01). The tensile strength of the PL implants was greater than that of the MM implants. At 90 days, the tensile strength of the PL implants was mean equals 33.11 N and of the MM implants, mean equals 22.65 N (Mann-Whitney test p < 0.001). CONCLUSIONS The tissue integration of the PL and MM implants differed; fewer visceral adhesions formed on MM than on PL; the macrophage reaction was not determinant of the success of failure of either biomaterial; and the tensile strength of the prosthesis-receptor tissue interface was much greater in the PL implants than in the MM implants.

Simple sequence repeat primers used in polymerase chain reaction amplifications to study genetic diversity in barley.

Abstract: In combination with oligonucleotides of arbitrary sequence, 5′ anchored oligonucleotides based on simple sequence repeats were used in polymerase chain reaction amplifications to produce barley DNA fingerprints. The aim of this work was (i) to develop a simple nonradioactive experimental procedure to reveal polymorphism in regions containing SSRs, (ii) to determine the genetic nature of polymorphisms, and (iii) to investigate the efficacy of polymorphisms contained in such fingerprints in disclosing genetic relationships between 14 European barley cultivars with known pedigrees. Different 10-mer oligonucleotides containing a dinucleotide motif were used as single primers and also in pairs with 10-mer oligonucleotides of arbitrary sequence. Further, the arbitrary oligonucleotides were used as single primers to produce RAPDs. Thirteen combinations of primers containing either GT(CA)4 or GC(CA)4 were selected on the basis of number and intensity of scorable bands in silver-stained 7% polyacrylamide gels. Of ...

Intrauterine growth retardation at term: association between anthropometric and endocrine parameters

Abstract: Objective. To investigate the endocrine profile of the intrauterine growth retardation newborns and its association with anthropometric parameters at birth.Study design. This is a case-control study of 76 full term gestations, of which 31 were diagnosed as intrauterine growth retardation (IUGR) confirmed at birth, and 45 as normal births. Insulin, insulin-like growth factor I (IGF-I), growth hormone (GH), thyroid stimulating hormone (TSH), hydrocortisone, prolactin and 15 metabolic parameters were measured in maternal blood antepartum, amniotic fluid and umbilical cord blood at birth.Results. Blood taken from the umbilical cord in the IUGR group had statistically significant lower levels of IGF-I, insulin and TSH, but higher levels of GH. In amniotic fluid and maternal blood, IUGR babies had lower levels of cortisol. The changes in GH and glucose levels in cord blood of IUGR babies were independently associated to birth weight variability (Adjusted regression coefficient-squared=0.09 and 0.17 respectively...

Decreased Levels of Blood Trypanosome Infection Correlate with Female Expression of a Male Secondary Sexual Trait: Implications for Sexual Selection

Abstract: Hamilton & Zuk proposed that conspicuous male plumages of birds could be reliable signals of parasite resistance. We examined this prediction in a system involving blood trypanosomes in a passerine bird, the pied flycatcher (Ficedula hypoleuca). Trypanosome prevalence and intensity of infections were unrelated to male age and expression of a secondary sexual trait. However, trypanosome infections were absent or maintained at significantly lower levels in females expressing a male trait which females have been shown to prefer in males. This relation held even after controlling for the significant effects that female age had on both the expression of the male trait and the rate of parasitism by trypanosomes. Given that the male trait is heritable and genetically correlated between the sexes, and there exists assortative mating based on white patch size and/or expression, a system of mutual mate choice may exist. In such a system, the benefits accrued to both males and females would be a higher chance of successful mating and the acquisition of genes for resistance to parasites to transmit to the offspring. These data thus support by an alternate route Hamilton & Zuk's hypothesis on parasite-driven sexual selection.

Identification of the Product of ndhA Gene as a Thylakoid Protein Synthesized in Response to Photooxidative Treatment

Abstract: A 76 amino acid sequence of NDH-A (the protein encoded by plastid ndhA gene) from barley (Hordeum vulgare L.) was expressed as a fusion protein with beta-galactosidase in E. coli. The corresponding antibody generated in rabbits was used to investigate localization, expression and synthesis in vitro of NDH-A. NDH-A was identified as a 35 kDa polypeptide localized in thylakoid membrane. Western blots shows a large increase in NDH-A levels when barley leaves were incubated under photooxidative conditions, which was more pronounced in mature-senescent leaves than in young leaves. Immunoprecipitation of the [35S]methionine labelled proteins, synthesized in vitro by isolated chloroplasts, demonstrated the synthesis in chloroplasts of the NDH-A 35 kDa polypeptide when barley leaves had been incubated under photooxidative conditions. The results indicate that ndh genes may be involved in the protection of chloroplasts against photooxidative stress, particularly in mature-senescent leaves.

Rate-limiting steps of tyrosinase-modified electrodes for the detection of catechol.

Abstract: The response currents obtained for tyrosinase-modified Teflon/graphite, carbon paste, and solid graphite electrodes in the presence of catechol are analyzed primarily using rotating disk electrode experiments The rate-limiting steps, such as the electrochemical reduction of o-quinones and the enzymatic reduction of oxygen as well as the enzymatic oxidation of catechol, are theoretically considered and experimentally demonstrated for the different electrode configurations

A molecular linkage map of rye.

Abstract: A genetic map of six chromosomes of rye, (all of the rye chromosomes except for 2R), was constructed using 77 RFLP and 12 RAPD markers. The map was developed using an F2 population of 54 plants from a cross between two inbred lines. A rye genomic library was constructed as a source of clones for RFLP mapping. Comparisons were made between the rye map and other rye and wheat maps by including additional probes previously mapped in those species. These comparisons allowed (1) chromosome arm orientation to the linkage groups to be given, (2) the corroboration of several evolutionary translocations between rye chromosomes and homoeologous chromosomes of wheat; (3) an increase in the number of available markers for target regions of rye that show colinearity with wheat. Inconsistencies in the location of markers between the wheat and rye maps were mostly detected by multi-copy probes.

Synthesis and DNA Binding Properties of γ-Carbolinium Derivatives and Benzologues

Abstract: The 5H-pyrido[4,3-b]indole, 11H-indolo[3,2-c]quinoline, 5H-benzo[f]pyrido[4,3-b]indole, and 13H-benz[5,6]indolo[3,2-c]quinoline heteroaromatic nuclei have been synthesized by the Graebe−Ullmann method by classical heating or under microwave irradiation. These tri-, tetra-, and pentacyclic compounds were transformed into the corresponding cationic derivatives by N-alkylation, and the DNA-binding properties of the resulting cationic systems were examined using UV−vis spectroscopy, viscometric determinations, and molecular modeling techniques. The tetracyclic cations were transformed into bis-salts by means of a diethyl bispiperidine rigid chain and a more flexible polyamide linker, but the low solubility of these bis-salts made the study of their bisintercalating properties difficult.

Resistant Starch Formation: Standardization of a High-Pressure Autoclave Process

Abstract: Gelatinization was studied in a high-pressure autoclave (HPA) process. Temperature, stirring, and pressure conditions were continuously controlled during gelatinization. The formation of resistant starch (RS) in standards of potato (amylose, amylopectin, and starch) was investigated during autoclaving in the HPA process and cooling. The results obtained showed that the higher the amylose contents, the larger the RS yield. RS yields obtained in the HPA process were greater than the ones obtained using a boiling water bath as gelatinization system. Scanning electronic microscopy studies of native and retrograded starch showed structural differences between the two states. Keywords: Resistant starch; amylose; amylopectin; starch; gelatinization; retrogradation

Induction of β-oxidation enzymes and microbody proliferation in Aspergillus nidulans

Abstract: Aspergillus nidulans is able to grow on oleic acid as sole carbon source. Characterization of the oleate-induced β-oxidation pathway showed the presence of the two enzyme activities involved in the first step of this catabolic system: acyl-CoA oxidase and acyl-CoA dehydrogenase. After isopicnic centrifugation in a linear sucrose gradient, microbodies (peroxisomes) housing the β-oxidation enzymes, isocitrate lyase and catalase were clearly resolved from the mitochondrial fraction, which contained fumarase. Growth on oleic acid was associated with the development of many microbodies that were scattered throughout the cytoplasm of the cells. These microbodies (peroxisomes) were round to elongated, made up 6% of the cytoplasmic volume, and were characterized by the presence of catalase. The β-oxidation pathway was also induced in acetate-grown cells, although at lower levels; these cells lacked acyl-CoA oxidase activity. Nevertheless, growth on acetate did not cause a massive proliferation of microbodies in A. nidulans.

Physical mapping of repetitive DNA sequences and 5S and 18S-26S rDNA in five wild species of the genus Hordeum

Abstract: The genetic relationships between several wild species and subspecies of the genus Hordeum were assessed using fluorescence in situ hybridization (FISH). Plant material included natural populations of wild barley growing in Spain of the annual species, H. marinum ssp. marinum (2n = 14) and gussoneanum (2n = 14), and H. murinum ssp. murinum (2n = 28), and leporinum (2n = 28) and the perennial species H. bulbosum (2n = 14) and H. secalinum (2n = 28), plus the South American perennial species H. chilense (2n = 14). FISH was used to locate the chromosomal sites of two rDNA multigene families 5S and 18S-26S (pTa71 and pTa794) and three repetitive DNA sequences (pSc119.2, pAs1 and pHch950) isolated from different species and genera. The seven chromosomes of the diploid species were readily distinguished by their external morphology and hybridization patterns to pTa71, pTa794, pSc119.2 and pAs1. These DNA probes were also useful for the identification of homologous chromosomes and in differentiating these from unidentified chromosomes in the tetraploid taxa. The use of the probe pHch950 permitted intergenomic differentiation in tetraploids and supports the diphyletic origin of H. murinum and H. secalinum. The in situ experiments yielded the following conclusions: (1) differences between the sub-species marinum and gussoneanum; (2) close relationships between the subspecies murinum and leporinum; and (3) major differences in physical mapping between H. bulbosum and the remaining taxa. The genomic and phylogenetic relationships between taxa, as inferred from the results, are discussed.

Mechanisms of allodynia: interactions between sensitive mechanoreceptors and nociceptors.

Abstract: We examined whether stimulation of sensitive mechanoreceptors from an area of allodynia evokes nociceptor activity expressed as axon reflexes. Experiments were conducted on human volunteers. Cutaneous blood flow was measured with a laser Doppler flowmeter. Allodynia was induced with mustard oil (25-100%) or by intradermal injections of capsaicin (25-50 micrograms) in the skin of the forearm or the hand. Tactile stimulation of normal skin or outside zones of allodynia did not evoke axon reflexes. The same stimulation in areas of allodynia evoked pain as well as axon reflexes. Cooling the area of primary hyperalgesia or blocking the A fibres in the nerve that innervated the allodynia area abolished the allodynia and the axon reflex. These results demonstrate central interactions between sensitive mechanoreceptors and nociceptors concomitant with the development of allodynia.

Using Citation Classics to study the incidence of serendipity in scientific discovery

Abstract: The main sociological, philosophical and historical approaches only ascribe a relative importance to the role of chance, error, or accident in scientific progress. The literature on this topic tends to be anecdotal, sometimes hagiographic and rarely systematic. The main goal of this paper is to introduce a new approach to the study of serendipity in scientific discovery. This new approach is based in the study of highly cited papers obtained from theCitation Classics feature ofCurrent Contents. This paper re-examines 205Citation Classics commentaries from the 400 most-cited papers in the recent history of science. Authors of 17Citation Classics commentaries (8.3%) mention some kind of serendipity in performing the research reported in the highly cited paper. Commentaries are classified and discussed in detail. In addition, I have examinated the original papers identified above. In 5 from the original highly cited papers authors explained or gave enough hints on the way the serendipitous discovery was done.

Parasites and the Ontogeny of Sexual Size Dimorphism in a Passerine Bird

Abstract: Explanations of sexual size dimorphism in animals have generally relied on theoretical predictions of sexual selection, niche differentiation, and sex ratio theories, whereas proximate influences on size dimorphisms are undescribed in wild populations. We describe the differential effects of mite nest ectoparasites on the growth of the tarsus, a measure of skeletal size, in nestling pied flycatchers, Ficedula hypoleuca, depending on sex. The detrimental effects of mites were suffered by males to a higher degree than females. It is proposed that parasites may interact with both host hormones and the host immune system to cause sexual size dimorphisms in young animals.

Laparoscopic Repair of Hernia of Foramen of Morgagni: A New Case Report

Abstract: A new case report of laparoscopic repair of a diaphragmatic hernia through the foramen of Morgagni in a 53-year-old woman is described. The patient had a successful recovery with no recurrence 2 years after surgery. The authors propose that the laparoscopic approach is an alternative to classical treatment for this kind of hernia.