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Search Results: 1 - 10 of 10323 matches for " Javier Llorca "
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Análisis de supervivencia en presencia de riesgos competitivos: estimadores de la probabilidad de suceso
Llorca,Javier; Delgado-Rodríguez,Miguel;
Gaceta Sanitaria , 2004, DOI: 10.1590/S0213-91112004000500009
Abstract: objective: to show the impact of competing risks of death on survival analysis. method: we provide an example of survival time without chronic rejection after heart transplantation, where death before rejection acts as a competing risk. using a computer simulation, we compare the kaplan-meier estimator and the multiple decrement model. results: the kaplan-meier method overestimated the probability of rejection. next, we illustrate the use of the multiple decrement model to analyze secondary end points (in our example: death after rejection). finally, we discuss kaplan-meier assumptions and why they fail in the presence of competing risks. conclusions: survival analysis should be adjusted for competing risks of death to avoid overestimation of the risk of rejection produced with the kaplan-meier method.
Fractura del hormigón en régimen elástico y lineal un ejemplo: la presa de Fontana
Elices, Manuel,Llorca, Javier,Ingraffea, Anthony R
Informes de la Construccion , 1985,
Abstract: Linear Elastic Fracture Mechanics can be applied to plain concrete provided the fracture process zone be small compared with the size of the structural element. In this situation the stress State at the tip of the crack can be characterized by means of the stress intensity factor. The first part of the paper considers modeling crack extension in concrete by the finite element method. The second part deals with an example problem, the cracked Fontana Dam. La Mecánica de la Fractura en régimen elástico y lineal es aplicable a grandes elementos de hormigón en masa porque la zona de fractura suele ser peque a en comparación con las dimensiones del elemento estructural y es posible caracterizar, en estos casos, el estado tensional en el fondo de una fisura mediante el factor de intensidad de tensiones. El artículo consta de dos partes: En la primera se describen las técnicas de elementos finitos utilizadas para modelizar la propagación de una fisura y en la segunda parte se comenta la aplicación de las mismas a un caso real, el estudio de una fisura en una presa de gravedad.
Decrease in tobacco consumption after treatment with topiramate and aripiprazole: a case report
Beatriz Arbaizar, Inés Gómez-Acebo, Javier Llorca
Journal of Medical Case Reports , 2008, DOI: 10.1186/1752-1947-2-198
Abstract: We report the case of a 34-year-old man who compulsively smoked 80 to 100 cigarettes each day. After receiving treatment with topiramate and aripiprazole, his tobacco consumption was dramatically reduced.Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and/or kainate blocking agents and a dopamine D2 receptor partial agonist may be novel instruments for nicotine abuse disorders.It is generally considered that the effect of drugs of abuse is focused towards mesolimbic dopamine (DA) reward circuitry; this is formed by the ventral tegmental area, which projects rostrally to the forebrain and limbic regions, such as the nucleus accumbens, amygdala and frontal cortex [1], and the glutamatergic neurotransmission system [2].We report a dramatic decrease in tobacco consumption in a patient under treatment with topiramate (an anticonvulsant with glutamatergic blocking properties) and aripiprazole (a selective DA D2 receptor partial agonist).A 34-year-old man was admitted after being found unconscious. He was diagnosed with metabolic coma and admitted to an intensive care unit for 9 days. He was discharged with a diagnosis of mild-moderate encephalopathy of probably mixed origin (hypoglycemia and anoxia); 1 mg haloperidol and 2 mg lormetazepam at bedtime were prescribed in addition to his usual treatment.The patient was seen at the emergency medical service 33 days after being discharged. He was suffering from hallucinosis and agitation. An increase in the haloperidol dose up to 4 mg/day was prescribed, and the patient was referred to a local community mental health center.The patient was a cocaine and alcohol addict and had previously received treatments for these addictions without success.His past history included diabetes mellitus type I, diabetic retinopathy, painful diabetic polyneuropathy being treated with 800 mg gabapentin three times a day, sexual dysfunction, alcoholic liver disease and asthmatic bronchitis.Three months later, he went to the community menta
Las variables meteorológicas no explican el gradiente norte-sur en la mortalidad por esclerosis múltiple en Espa?a
Guerrero-Alonso,Paula; Prieto-Salceda,Dolores; Llorca,Javier;
Gaceta Sanitaria , 2007, DOI: 10.1590/S0213-91112007000400011
Abstract: objectives: to determine whether weather conditions explain the north-south gradient in multiple sclerosis (ms) mortality described in spain. methods: the age-adjusted ms mortality rate by spanish provinces from 1975 to 1998 was correlated with several climatic variables. results: ms mortality was negatively correlated with minimum, average and maximum temperatures, the mean number of hours of sunshine, and the mean number of sunny days. a positive correlation was found with the average amount of rain. most correlations disappeared after adjusting by latitude. however, ms mortality was associated with latitude after adjusting by climatic factors. conclusions: the north-south gradient in ms mortality in spain cannot be fully explained by weather differences. therefore, other hypotheses are required to explain this association.
Estudios longitudinales: concepto y particularidades
Delgado Rodríguez,Miguel; Llorca Díaz,Javier;
Revista Espa?ola de Salud Pública , 2004, DOI: 10.1590/S1135-57272004000200002
Abstract: in this review the definition of ?longitudinal study? is analysed. most current textbooks on epidemiology do not define a longitudinal study, whereas statistical textbooks do. it is more common to talk about longitudinal data than about longitudinal studies. a longitudinal study implies the existence of repeated measurements (more than two) across follow-up. according to these ideas, a longitudinal study can be considered a subtype of cohort study that, in contrast with life-table cohort studies, allows inference to the subject level, to analyze changes in variables (exposures and outcomes) and transitions among different health states. the characteristics of this design force to paid special attention to quality control during data collection, losses during follow-up, and missing data in some measurements. the statistical analysis should take repeated measures into account, and it is what finally gives the longitudinal character to a study with repeated measurements.
Medición de las desigualdades en la edad de muerte: cálculo del índice de gini a partir de las tablas de mortalidad
Llorca,Javier; Prieto Salceda,Dolores; Delgado-Rodríguez,Miguel;
Revista Espa?ola de Salud Pública , 2000, DOI: 10.1590/S1135-57272000000100002
Abstract: the gini index has been used to gauge the concentration of different variables, including income, the mortality distribution and the spread of physicians. the use of the gini index for gauging the inequalities in the age of death based on actuarial mortality data. for this purpose, the 1990 age and gender-related mortality figures for each autonomous community were used. the inequalities in the number of years lived are greater among males than among females throughout all of the autonomous communities. the communities showing the longest life expectancies are those which have also been revealed to involve the least degree of inequality in the number of years lived, which therefore makes in possible to pinpoint health-care priorities in some cases. the gini index can be applied to age-related mortalitys for gauging the degree of inequality in the age of death and to pinpoint age groups on which to place priority with regard to health-care measures.
Medición de las desigualdades en la edad de muerte: cálculo del índice de gini a partir de las tablas de mortalidad
Llorca Javier,Prieto Salceda Dolores,Delgado-Rodríguez Miguel
Revista Espa?ola de Salud Pública , 2000,
Abstract: El índice de Gini se ha utilizado como medida de la concentración de diferentes variables, incluyendo los ingresos económicos, la distribución de la mortalidad y la distribución de médicos. Se describe el uso del índice de Gini para medir las desigualdades en la edad de muerte a partir de los datos de mortalidad actuariales. Para ello se emplean los datos de mortalidad por edad y sexo en cada Comunidad Autónoma espa ola en 1990. Las desigualdades en a os vividos son mayores en los varones que en las mujeres en todas las Comunidades Autónomas. Las Comunidades con mayor esperanza de vida tienen también menor desigualdad en los a os vividos, lo que permite, en algunas ocasiones, identificar prioridades sanitarias. El índice de Gini puede ser aplicado a las tasas de mortalidad por edad para medir el grado de desigualdad en la edad de muerte y para identificar grupos etarios para la actuación sanitaria prioritaria.
Pericellular innervation of neurons expressing abnormally hyperphosphorylated tau in the hippocampal formation of Alzheimer's disease patients
Lidia Blazquez-Llorca,Virginia Garcia-Marin,Javier DeFelipe
Frontiers in Neuroanatomy , 2010, DOI: 10.3389/fnana.2010.00020
Abstract: Neurofibrillary tangles (NFT) represent one of the main neuropathological features in the cerebral cortex associated with Alzheimer’s disease (AD). This neurofibrillary lesion involves the accumulation of abnormally hyperphosphorylated or abnormally phosphorylated microtubule-associated protein tau into paired helical filaments (PHF-tau) within neurons. We have used immunocytochemical techniques and confocal microscopy reconstructions to examine the distribution of PHF-tau-immunoreactive (ir) cells, and their perisomatic GABAergic and glutamatergic innervations in the hippocampal formation and adjacent cortex of AD patients. Furthermore, correlative light and electron microscopy was employed to examine these neurons and the perisomatic synapses. We observed two patterns of staining in PHF-tau-ir neurons, pattern I (without NFT) and pattern II (with NFT), the distribution of which varies according to the cortical layer and area. Furthermore, the distribution of both GABAergic and glutamatergic terminals around the soma and proximal processes of PHF-tau-ir neurons does not seem to be altered as it is indistinguishable from both control cases and from adjacent neurons that did not contain PHF-tau. At the electron microscope level, a normal looking neuropil with typical symmetric and asymmetric synapses was observed around PHF-tau-ir neurons. These observations suggest that the synaptic connectivity around the perisomatic region of these PHF-tau-ir neurons was apparently unaltered.
Adherence to highly active antiretroviral therapy in Spain: A meta-analysis
Ortego,Carmen; Huedo-Medina,Tania Bibiana; Vejo,Javier; Llorca,Francisco Javier;
Gaceta Sanitaria , 2011, DOI: 10.1590/S0213-91112011000400004
Abstract: objectives: to estimate the percentage of adherence to highly-active antiretroviral therapy (haart) in spanish observational studies and to identify the variables associated with adherence. methods: seven electronic databases were used to locate the studies. six inclusion criteria were established. two coders codified the variables independently. intercoder reliability was calculated. publication bias was analyzed through the begg, egger and trim and fill tests. homogeneity was evaluated using the q test and the l2 index. a random effects model was assumed to estimate both the overall percentage of adherence and to explain heterogeneity. results: this meta-analysis included 23 observational studies, yielding a total of 34 adherence estimates. the sample was composed of 9,931 hiv-positive individuals (72% men) older than 18 years under treatment with haart. the percentage of patients adhering to an intake of >90% of the prescribed antiretroviral drugs was 55%. wide heterogeneity was detected (i2=91.20; 95%ci: 88.75-93.13). adherence was mainly measured using a single strategy (47.8%), the most widely used being self-report (48.7%). in the univariate analysis, the following factors were significant: infection stages a (β=0.68, p <0.001) and b (β=-0.56, p <0.01), viral loads >200 copies/ml (β=-0.41, p <0.05) and <200 (β=0.39, p <0.05), and university education (β=-0.66, p<0.05). conclusions: the overall percentage of adherence was 55%, although this value may be an overestimate. adherence was associated with infection stage a and with a viral load of <200 copies/ml.
Correlation between endothelial function and carotid atherosclerosis in rheumatoid arthritis patients with long-standing disease
Carlos González-Juanatey, Javier Llorca, Miguel A González-Gay
Arthritis Research & Therapy , 2011, DOI: 10.1186/ar3382
Abstract: One hundred eighteen patients who fulfilled the 1987 American College of Rheumatology classification criteria for RA, had no history of CV disease and had at least one year of follow-up after disease diagnosis were randomly selected. Brachial and carotid ultrasonography were performed to determine FMD and carotid IMT, respectively.Carotid IMT values were higher and FMD percentages derived by performing ultrasonography were lower in individuals with a long duration from the time of disease diagnosis. Patients with a disease duration ≤ 7 years had significantly lower carotid IMT (mean ± SD) 0.69 ± 0.17 mm than those with long disease duration (0.81 ± 0.12 mm in patients with ≥ 20 years of follow-up). Also, patients with a long disease duration had severe endothelial dysfunction (FMD 4.0 ± 4.0% in patients with disease duration from 14.5 to 19.7 years) compared with those with shorter disease duration (FMD 7.4 ± 3.8% in patients with disease duration ≤ 7 years). Linear regression analysis revealed that carotid IMT was unrelated to FMD in the whole sample of 118 patients. However, carotid IMT was negatively associated with FMD when the time from disease diagnosis ranged from 7.5 to 19.7 years (P = 0.02).In patients with RA without CV disease, endothelial dysfunction and carotid IMT increased with the duration of RA. The association between FMD and carotid IMT values was observed only in patients with long disease duration.Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with increased incidence of cardiovascular (CV) mortality [1,2]. This is the result of accelerated atherosclerosis [3]. Because of the high incidence of CV events observed in patients with RA, an important step forward might be to identify high-risk individuals who would benefit from active therapy to prevent clinical disease. In this regard, several noninvasive imaging techniques offer clinicians a unique opportunity to study the relationship of surrogate markers to the development
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