Showing papers by "Autonomous University of Barcelona published in 1996"

Routes of Infection, Viremia, and Liver Disease in Blood Donors Found to Have Hepatitis C Virus Infection

Abstract: Background For many people infected with the hepatitis C virus (HCV), the route of exposure, risk of transmission, and severity of associated liver disease are unknown. We studied these variables in people who donated blood voluntarily. Methods Blood donors who tested positive for HCV antibodies on enzyme immunoassay were classified according to whether the results of a confirmatory second-generation recombinant immunoblot assay (RIBA) for HCV were positive, negative, or indeterminate. The evaluations also included an assessment of risk factors, a physical examination, serial determinations of alanine aminotransferase levels and HCV serologic assays, a polymerase-chain-reaction assay for HCV RNA, testing of sexual contacts and family members, and liver biopsies in some participants who were HCV-positive by RIBA. Results A total of 481 donors were studied, among whom 248 were positive for HCV by RIBA, 102 had indeterminate results, and 131 were HCV-negative. In a logistic-regression analysis, significant r...

Modification of empiric antibiotic treatment in patients with pneumonia acquired in the intensive care unit. ICU-Acquired Pneumonia Study Group.

Abstract: To assess the frequency of and the reasons for changing empiric antibiotics during the treatment of pnnumonia acquired in the intensive care unit (ICU). A prospective multicenter study of 1 year's duration. Medical and surgical ICUs in 30 hospitals all over Spain. Of a total of 16872 patients initially enrolled into the study, 530 patients developed 565 episodes of pneumonia after admission to the ICU. Empiric antibiotics were administered in 490 (86.7%) of the 565 episodes of pneumonia. The antimicrobials most frequently used were amikacin in 120 case, tobramycin in 110, ceftazidime in 96, and cefotaxime in 96. Monotherapy was indicated in 135 (27.6%) of the 490 episodes, a combination of two antibiotics in 306 episodes (62.4%), and a combination of three antibiotics in 49 episodes (10%). The empiric antibiotic treatment was modified in 214 (43.7%) cases because of isolation of a microorganism not covered by treatment in 133 (62.1%) cases, lack of clinical response in 77 (36%), and development of resistance in 14 (6.6%). Individual factors associated with modification of empiric treatment identified in the multivariate analysis were microorganism not covered (relative risk (RR)) 22.02; 95% confidence interval (CI) 11.54 to 42.60;p<0.0001), administration of more than one antimicrobial (RR 1.29; 95% CI 1.02 to 1.65;p=0.0018) attributable mortability was 16.2%.

Colossal magnetoresistance of ferromagnetic manganites: Structural tuning and mechanisms.

Abstract: The amplitude $\ensuremath{\Delta}\ensuremath{\rho}(T,H)/\ensuremath{\rho}$ and temperature ${T}_{M}$, where the colossal magnetoresistance (CMR) response of ${L}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ manganites are maximum, are found to be controlled by the radius of the lanthanide $({L}^{3+})$ which modifies the bending of the Mn-O-Mn bond. Increasing the bond distortion lowers ${T}_{M}$ and enhances $\ensuremath{\Delta}\ensuremath{\rho}(T,H)/\ensuremath{\rho}$. Enhanced CMR arises from (1) a shift to lower temperatures of ${T}_{M}$, (2) a reduced mobility of the doping holes, and (3) an increase of the coupling between itinerant and localized electrons. The resistivity $\ensuremath{\rho}\left(H\right)$ follows an $\ensuremath{\approx}{\mathrm{BM}}^{2}\left(H\right)$ law and the parameter $B$ is also tuned by the Mn-O-Mn bond angle. The narrowing of the electronic bandwidth is the fundamental parameter controlling the observed CMR.

Validity and reliability of the St George's Respiratory Questionnaire after adaptation to a different language and culture: the Spanish example

Abstract: We describe the adaptation into Spanish of the St George's Respiratory Questionnaire (SGRQ), a self-administered questionnaire developed by Jones et al. (1991) covering three domains of health in airways disease patients: symptoms, activity and impacts. For the adaptation, the forward and back-translation method by bilinguals was used, together with professional committee and lay panel. Once tested for feasibility and comprehension, 318 male chronic obstructive pulmonary disease (COPD) patients with a wide range of disease severity completed the Spanish version of the SGRQ. The clinical status of the patients was evaluated concurrently with the measurement of health status. Lung function was assessed in the 2 months before or after the questionnaire administration. The Spanish version of the SGRQ was acceptable and easy to understand. Cronbach's alpha reliability coefficient was 0.94 for the overall scale and 0.72 for "Symptoms", 0.89 for "Activity", and 0.89 for "Impacts" subscales. Correlation coefficients between the overall score and dyspnoea and % forced expiratory volume in one second (FEV1) were 0.59 and -0.45, respectively, and these correlations were higher than those observed between the clinical variables and the Nottingham Health Profile, a generic measure of health-related quality of life. Results of the study suggest that the Spanish version of the SGRQ is conceptually equivalent to the original, and similarly reliable and valid. Although further studies should complete the adaptation work, results suggest that the SGRQ may already be used in Spain and in international studies involving Spanish respiratory patients. According to the present approach, it appears to be feasible to adapt a specific questionnaire on health-related quality of life in respiratory disease to another language and culture.

Is the income elasticity of environmental improvements less than one

Abstract: We estimated the income elasticity of environmental improvements for a number of European data-sets. The value of this parameter is consistently found to be less than one, with few exceptions. Our findings are compared with state-of-the-art contingent valuation studies from other countries. We also compared our findings with those reported in the literature on charitable donations and corporate donations. These studies show a similar pattern; donations decrease as a percentage of income, as income increases.

Palladium-Catalyzed Suzuki-Type Self-Coupling of Arylboronic Acids. A Mechanistic Study

Abstract: Symmetrical biaryls are formed from arylboronic acids both under tetrakis(triphenylphosphine)palladium and under palladium(II) acetate catalysis. The principal mechanistic features of these self-couplings have been determined.

Stochastic foundations of fractional dynamics

Abstract: It is shown that fractional diffusion equations arise very naturally as the limiting dynamic equations of all continuous time random walks with decoupled temporal and spatial memories and with either temporal or spatial scale invariance (fractal walks), thus enlarging their stochastic foundations hitherto restricted to a particular case of fractal walk [R. Hilfer and L. Anton, Phys. Rev. E 51, R848 (1995)].

Hypothalamic-pituitary-adrenal response to chronic stress in five inbred rat strains: Differential responses are mainly located at the adrenocortical level

Abstract: The effects of chronic stress on the hypothalamic-pituitary-adrenocortical (HPA) axis were studied in five inbred rat strains, i.e. Brown Norway (BN), Fischer (FIS), Lewis (LEW), Spontaneously Hyperte

Analysis of protein conformational characteristics related to thermostability

Abstract: The thermal stability of proteins was studied, 195 single amino acid residue replacements reported elsewhere being analysed for several protein conformational characteristics: type of residue replacement; conservative versus nonconservative substitution; replacement being in a homologous stretch of amino acid residues; change in hydrogen bond, van der Waals and secondary structure propensities; solvent-accessible versus inaccessible replacement; type of secondary structure involved in the substitution; the physico-chemical characteristics to which the thermostability enhancement can be attributed; and the relationship of the replacement site to the folding intermediates of the protein, when known. From the above analyses, some general rules arise which suggest where amino acid substitutions can be made to enhance protein thermostability: substitutions are conservative according to the Dayhoff matrix; mainly occur on conserved stretches of residues; preferentially occur on solvent-accessible residues; maintain or enhance the secondary structure propensity upon substitution; contribute to neutralize the dipole moment of the caps of helices and strands; and tend to increase the number of potential hydrogen bonding or van der Waals contacts or improve hydrophobic packing.

Expression of an estrogen receptor by human coronary artery and umbilical vein endothelial cells

Abstract: Background Premenopausal women have much lower susceptibility to coronary artery disease than do men or postmenopausal women. It has been proposed that estrogen plays a role in cardioprotection, but little information is available regarding the mechanism by which estrogen may help to protect the vasculature. Here, we describe an estrogen receptor (ER) in human coronary artery and umbilical vein endothelial cells. Methods and Results Human umbilical vein endothelial cells and human coronary artery endothelial cells were cultured in hormone-free medium for 48 hours before experiments. Estradiol (3.7 nmol/L) added to cultures promoted proliferation by a mechanism that is inhibited by the specific ER antagonist ICI182,780. Estradiol-treated cells incorporated twice the [3H]thymidine of hormone-free cells; this increase was prevented by ICI182,780. Endothelial cells from both sources stained in a nuclear pattern with an ER-specific antibody. Ribonuclease protection assay detected mRNA for the ER. Ligand-bindin...

The Ansó transect of the southern Pyrenees : basement and cover thrust geometries

Abstract: A balanced geological section through the western central Pyrenees allows the Alpine geometry of Hercynian basement to be determined. This shows marked differences with other transects of the southern part of the chain. Basement-involved thrust sheets do not form an antiformal stack, but are imbricated and define steps separated by frontal culmination limbs. Basement thrusts propagate upwards and have formed distinct thrust systems in the cover. In this transect, the North Pyrenean Zone is bounded to the south by gently dipping thrusts of large displacement, and the Axial Zone massif, at its western termination area, is a flat-topped culmination caused by a single thrust fault, the Gavarnie thrust. This thrust emerges to the south in the interior of the syntectonic Jaca Basin, the geometry of which is also controlled by underlying basement thrusts. Various generations of structures can be correlated with distinct episodes of syntectonic sedimentation. A sequential restoration of the section illustrates how successive foreland sedimentary wedges were generated and progressively involved in deformation. Tectonic shortening is 48 km, almost half of that estimated further to the east for the southern Pyrenees. The structure deduced at the ECORS-Pyrenees seismic section cannot be translated to this transect.

Evidence from transgenic mice that glucokinase is rate limiting for glucose utilization in the liver.

Abstract: To study the role of glucokinase (GK) in the control of glucose metabolism in the liver, transgenic mice were generated in which GK was overexpressed under control of the P-enolpyruvate carboxykinase gene promoter. Whereas the expression of the GK gene in starved control mice was blocked, this promoter was able to direct the expression of the enzyme to the liver of starved transgenic mice. Furthermore, starved transgenic mice showed levels of GK activity fourfold higher than those of starved control and similar to those of fed control. This activation of GK led to an increase in the intracellular concentration of glucose 6-phosphate, which was also related to an induction of glycogen accumulation. In addition, L-pyruvate kinase (L-PK) activity increased in transgenic mice, which when starved showed similar levels of activity to control fed mice. The induction of L-PK caused an increase in the hepatic lactate concentration. Furthermore, hepatocytes in primary culture from transgenic mice incubated with 20 mM glucose produced levels of lactate threefold higher than controls, but no difference was noted when the hepatocytes from control and transgenic mice were incubated with 2 mM glucose. These results demonstrated in vivo that the activation of GK is a rate-limiting step in the induction of glycolysis and glycogen synthesis. These changes in liver glucose metabolism led to a marked reduction in blood glucose (30%) and insulin (40%) concentrations. Furthermore, transgenic mice showed lower levels of blood glucose after an intraperitoneal glucose tolerance test, indicating that GK overexpression caused an increase in blood glucose disposal by the liver. All these findings show the key role of liver GK in the control of whole-body glucose homeostasis.-Ferre, T., Riu, E., Bosch, F., Valera, A. Evidence from transgenic mice that glucokinase is rate limiting for glucose utilization in the liver.

Relevance, discourse and the ‘hot’ stable core social representations—A structural analysis of word associations

Abstract: This paper presents an investigation of the structure of word associations dependent on the context in which they are assessed. Respondents from Spain and Nicaragua produced free associations about war and peace. Word associations about each of the two stimulus words were produced either spontaneously or within the context of a distracting priming condition in contrast to the association task. The semantic space for each stimulus word (war, peace) is analysed to find substructures of words which remain stable across contexts. These substructures or stable cores are taken to indicate a well-structured social representation as opposed to a loosely organized knowledge domain. Such cores were found for associations about war in both countries, but for peace in the Nicaraguan sample only. This finding is interpreted as a consequence of public discourse and symbolic coping with relevant or threatening objects or phenomena. Stable cores were found to consist primarily of ‘hot’ words, i.e. words which are proximal to an individual's experience. More intellectual and distant (‘cold’) words did not enter the stable core. Results are discussed in terms of the central core theory of social representations and of numerical consensus being an insufficient criterion for social representations.

Relationship between photosynthetic radiation-use efficiency of barley canopies and the photochemical reflectance index (PRI)

Abstract: Some processes of excess radiation dissipation have been associated with changes in leaf reflectance near 531 nm. We aimed to study the relations between the photochemical reflectance index (PRI) derived from this signal, and photosynthetic radiation-use efficiency (defined as net CO 2 assimilation rate/incident photon flux density) in a cereal canopy. Measurements of reflectance, fluorescence, gas exchange and xanthophyll cycle pigments were made in the morning, midday and afternoon in barley canopies with two levels of nitrogen fertilization. The photosynthetic radiation-use efficiency decreased at midday, mainly in the third leaf, in both treatments, with lower values for the nitrogen deficient leaves. The zeaxanthin content showed the inverse pattern, increasing at midday and in the nitrogen deficient treatment. The photosynthetic radiation-use efficiency was well correlated with the epoxidation state, EPS (violaxanthin + 0.5 antheraxanthin)/(violaxanthin + antheraxanthin + zeaxanthin). The PRI [here defined as (R 539 - R 570 )/(R 539 + R 570 )] was significantly correlated with epoxidation state and zeaxanthin and with photosynthetic radiation-use efficiency. These results validate the utility of PRI in the assessment of radiation-use efficiency at canopy level.

Correction of diabetic alterations by glucokinase

Abstract: Hyperglycemia is a common feature of diabetes mellitus. It results from a decrease in glucose utilization by the liver and peripheral tissues and an increase in hepatic glucose production. Glucose phosphorylation by glucokinase is an initial event in glucose metabolism by the liver. However, glucokinase gene expression is very low in diabetic animals. Transgenic mice expressing the P-enolpyruvate carboxykinase/glucokinase chimeric gene were generated to study whether the return of the expression of glucokinase in the liver of diabetic mice might prevent metabolic alterations. In contrast to nontransgenic mice treated with streptozotocin, mice with the transgene previously treated with streptozotocin showed high levels of both glucokinase mRNA and its enzyme activity in the liver, which were associated with an increase in intracellular levels of glucose 6-phosphate and glycogen. The liver of these mice also showed an increase in pyruvate kinase activity and lactate production. Furthermore, normalization of both the expression of genes involved in gluconeogenesis and ketogenesis in the liver and the production of glucose and ketone body by hepatocytes in primary culture were observed in streptozotocin-treated transgenic mice. Thus, glycolysis was induced while gluconeogenesis and ketogenesis were blocked in the liver of diabetic mice expressing glucokinase. This was associated with normalization of blood glucose, ketone bodies, triglycerides, and free fatty acids even in the absence of insulin. These results suggest that the expression of glucokinase during diabetes might be a new approach to the normalization of hyperglycemia.

Effectiveness of Cloxacillin with and without Gentamicin in Short-Term Therapy for Right-Sided Staphylococcus aureus Endocarditis: A Randomized, Controlled Trial

Abstract: Background It is often difficult to administer extended antibiotic therapy in the hospital for right-sided Staphylococcus aureus endocarditis. Although the effectiveness of single-drug therapy given for 4 to 6 weeks and that of two-drug therapy given for 2 weeks have been shown, no data are available on the effectiveness of short-course single-drug therapy. Objective To compare the efficacy of cloxacillin alone with that of cloxacillin plus gentamicin for the 2-week treatment of right-sided S. aureus endocarditis in intravenous drug users. Design Open, randomized study. Setting An academic tertiary care hospital in Barcelona, Spain. Patients 90 consecutive intravenous drug users who had isolated tricuspid valve endocarditis caused by methicillin-susceptible S. aureus, had no allergy to study medications, and had no systemic infectious complications that required prolonged therapy. An efficacy subset consisted of 74 of these patients who did not meet an exclusion criterion. Intervention Cloxacillin (2 g intravenously every 4 hours for 14 days) alone or combined with gentamicin (1 mg/kg of body weight intravenously every 8 hours for 7 days). Measurements Clinical or microbiological evidence of active infection after 2 weeks of therapy, relapse of staphylococcal infection, or death. Results In an analysis of the efficacy subset, treatment was successful in 34 of the 38 patients who received cloxacillin alone (89% [95% CI, 75% to 97%]) and 31 of the 36 patients who received cloxacillin plus gentamicin (86% [CI, 71% to 95%]). Three patients died: one in the cloxacillin group and two in the combination therapy group. Of the 37 patients who completed 2-week treatment with cloxacillin, 34 (92%) were cured, and 3 (8%) needed prolonged treatment to cure the infection. Of the 34 patients who completed 2-week treatment with cloxacillin plus gentamicin, 32 (94%) were cured and 2 (6%) required treatment for 4 weeks. One patient in the combination group had relapse. Conclusions A penicillinase-resistant penicillin used as single-agent therapy for 2 weeks was effective for most patients with isolated tricuspid endocarditis caused by methicillin-susceptible S. aureus. Adding gentamicin did not appear to provide any therapeutic advantages. Additional studies to confirm the therapeutic equivalence of short-course therapy with penicillinase-resistant penicillin alone and therapy with combined regimens are warranted.

Air pollution and mortality in Barcelona

Abstract: STUDY OBJECTIVES: Studies conducted in Barcelona reported a short term relation between daily air pollutant values and emergency department admissions for exacerbation of chronic obstructive pulmonary diseases and asthma. Air pollution in Barcelona is mainly generated by vehicle exhaust and is below the World Health Organization air quality guidelines. The acute relation between air pollution and mortality was assessed. DESIGN: Daily variations in total mortality, mortality in subjects older than 70 years, and cardiovascular and respiratory mortality were related with daily variations in air pollutants for the period 1985-91, using autoregressive Poisson regression models that allow to control for temperature, relative humidity and variables handling temporal and autoregressive patterns. MAIN RESULTS: Black smoke and sulphur dioxide (SO2) were related to total mortality (relative risks (RR) for 100 micrograms/m3 = 1.07 and 1.13 respectively), elderly mortality (RR = 1.06 and 1.13), cardiovascular mortality (RR = 1.09 and 1.14), and respiratory mortality (RR = 1.10 and 1.13); all the associations being statistically significant, except for respiratory mortality (p = 0.07). The association between SO2 and respiratory mortality was stronger in summer (1.24, p 0.1). Oxidant pollutants (nitrogen dioxide and ozone) were positively related with elderly mortality (RR = 1.05 and 1.09, respectively) and cardiovascular mortality (RR = 1.07 and 1.09) during the summer (p < 0.05), but not during the winter. CONCLUSIONS: Current air pollutant levels were related to mortality in Barcelona. These results were consistent with similar studies in other cities and coherent with previous studies with emergency room admissions in Barcelona.

La teoría de redes sociales

Abstract: La teoria de redes sociales constituye un buen ejemplo de un tipo de aproximacion en que, en teoria, aparato conceptual metodos y tecnicas de investigacion han estado mutuamente sostenidos y generados. La perspectiva innovadora que aporta esta teoria es la relacional dentro de una vocacion claramente estructural, es decir, aquella en que los vinculos o las relaciones entre entidades son unidades basicas de recogida de informacion y del analisis. En este articulo se hace una introduccion general a la teoria de redes; mas adelante, en otros numeros de la revista, se aportaran analisis empiricos.

On the nonexistence, existence and uniqueness of limit cycles

Abstract: We present two new criteria for studying the nonexistence, existence and uniqueness of limit cycles of planar vector fields. We apply these criteria to some families of quadratic and cubic polynomial vector fields, and to compute an explicit formula for the number of limit cycles which bifurcate out of the linear centre , when we deal with the system . Moreover, by using the second criterion we present a method to derive the shape of the bifurcated limit cycles from a centre.

Gamma Rays from SN 1987A due to Pseudoscalar Conversion

Abstract: A light pseudoscalar coupled to two photons would be copiously emitted by the core of a supernova. Part of this flux would be converted to $\ensuremath{\gamma}$ rays by the galactic magnetic field. Measurements on the SN 1987A $\ensuremath{\gamma}$-ray flux by the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite already imply a bound on the coupling $gl3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}{\mathrm{GeV}}^{\ensuremath{-}1}$. The improved generation of satellite-borne detectors, like EGRET or the project GLAST, could be able to detect a pseudoscalar-to-photon signal from a nearby supernova, for allowed values of $g$.

Captopril reduces the risk of nephropathy in IDDM patients with microalbuminuria

Abstract: In insulin-dependent diabetes mellitus (IDDM), microalbuminuria predicts renal and cardiovascular disease. We report a combined analysis of 235 normotensive IDDM patients with microalbuminuria who participated in two 24-month double-blind, randomised, placebo-controlled trials to assess the effects of captopril 50 mg twice daily on the progression to overt clinical albuminuria. Of the 225 patients who were evaluable on an intent to treat basis, 25 of 114 placebo-treated patients (21.9%) and 8 of 111 captopril-treated patients (7.2%) progressed to persistent clinical albuminuria. The risk of progression over 24 months was significantly reduced by captopril (p = 0.004) with a risk reduction of 69.2% (95% confidence interval (CI): 31.7 to 86.1%). This degree of risk reduction remained at the same level (62.9% [16.1-83.6%], p = 0.017) after adjustment for differences in time-varying mean arterial blood pressure. Albumin excretion rate increased by an average of 14.2% [3.1-26.5%] per year in the placebo-treated group compared with a reduction of 9.6% [-18.6-0.4%] per year in the captopril-treated group (p = 0.002). The rate of fall of creatinine clearance tended to be faster in the placebo-treated group than in the captopril-treated group (-6.4 [-10.2--2.5] vs -1.4 [-5.3-2.6] ml . min(-1). 1.73 m(-2), p = 0.07). Baseline albumin excretion rate (p < 0.0001) and glycated haemoglobin (p = 0.03) were independent predictors of progression to clinical albuminuria and changes in mean arterial blood pressure (p = 0.02) and serum cholesterol level (p = 0.003) were significantly associated with percentage changes in albumin excretion rate. Captopril reduces the risk of progression to overt nephropathy in IDDM patients with microalbuminuria, an effect partly independent of its blood pressure-lowering effects.

Herbicide-induced DNA damage in human lymphocytes evaluated by the single-cell gel electrophoresis (SCGE) assay

Abstract: The genotoxicity of the herbicides, alachlor, atrazine, maleic hydrazide, paraquat and trifluralin has been evaluated in the single-cell gel electrophoresis (SCGE) assay by using human peripheral blood lymphocytes. All treatments were conducted with and without the presence of an external bioactivation source (S9 mix). The results indicate that all the herbicides tested are able to give positive results by increasing the comet tail length, which would confirm both the genotoxicity of the herbicides and the sensitivity of the assay in front of these chemicals. Alachlor and atrazine give similar results in treatments with and without S9, while when the S9 mix was not used paraquat and trifluralin genotoxicity was higher. On the other hand, although maleic hydrazide genotoxicity was higher when S9 mix was used at normal pH (7.4), our data show that its genotoxicity depends largely on the pH solution, increasing as the pH decreased.