Ocular exposure to infectious laryngotracheitis virus alters leukocyte subsets in the head-associated lymphoid tissues and trachea of 6-week-old White Leghorn chickens.

Infectious laryngotracheitis virus (ILTV), an alphaherpesvirus, causes acute respiratory disease primarily infecting the upper respiratory tract and conjunctiva. Administration of live attenuated ILTV vaccines via eye drop, drinking water, or by coarse spray elicits protective mucosal immunity in the head-associated lymphoid tissues (HALT), of which conjunctiva-associated lymphoid tissue (CALT) and the Harderian gland (HG) are important tissue components. The trachea, a non-lymphoid tissue, also receives significant influx of inflammatory cells that dictate the outcome of ILTV infection. The objective of this study was to evaluate leukocyte cellular and phenotypic changes in the CALT, HG and trachea following ocular infection with a virulent ILTV strain. At 1, 3, 5, 7 and 9 days post-infection, CALT, HG, and trachea of 6-week-old specific pathogen free (SPF) chickens ocularly-exposed to vehicle or virulent ILTV strain 63140 were dissociated, the cells enumerated and then phenotyped using flow cytometry. The CALT had the highest viral genomic load, which peaked on day 3. In ILTV-infected birds, the CALT had a decreased percentage of leukocytes. This was reflected by decreased numbers of MHCI+MHCII-, MHCI+MHCIIlow+, and CD4+ cells, while IgM+ and MHCI+MHCIIHigh+ expressing cell populations increased. In the HG, the most notable change in cells from ILTV-infected birds was a decrease in IgM expressing cells and histologically, an increase in Mott cells. In summary, an acute, ocular exposure to ILTV strain 63140 in young birds shifts subsets of lymphocyte populations in the CALT and HG with minimal impact on the trachea.

Evaluation of unenhanced post-mortem computed tomography to detect chest injuries in violent death.

PURPOSE: The aim of this study was to assess the performances of unenhanced post-mortem computed tomography (CT) to detect thoracic injuries in violent death. MATERIALS AND METHODS: Retrospectively, we conducted a review of unenhanced CT scans of 67 victims of violent deaths with thoracic injuries and compared CT findings with the results of clinical autopsy. Our gold standard was a comparison of CT scans with autopsy discussed in a monthly forensic radiology multidisciplinary team meeting (MDTM). The data were collected by organ system: heart, pericardium, aorta, lungs, pleura, bone, and diaphragm and performance indices (sensitivity, specificity, accuracy) were calculated. RESULTS: Pleural (59/67) and bone (55/67) injuries detected on CT were also found at autopsy and confirmed by the MDTM (sensitivity and specificity 100%). Seventeen out of 67 diaphragmatic lesions were visible on CT. Eighteen out of 67 were confirmed during MDTM after autopsy, yielding overall sensitivity of 94% and specificity of 98%. Forty out of 67 lung contusions were found on CT with two false positives and one false negative yielding 95% sensitivity for CT with a specificity of 96%, and accuracy of 95%. Fourteen out of 67 aortic injuries were found on CT compared to 19 confirmed during MDTM (sensitivity 74%, specificity 85%, accuracy 82%). In terms of pericardial lesions, 19/67 were found on CT and 20 on autopsy and confirmed during MDTM (sensitivity 80%, specificity 94%, accuracy 85%). Ten out of 10/67 cardiac lesions were visible on CT imaging and 15 found on autopsy and confirmed during MDTM (sensitivity 57%, specificity 94%, accuracy 81%). CONCLUSION: Unenhanced post-mortem CT performs well to detect pleural, pulmonary, bone and diaphragmatic injuries but less well to identify cardiac and aortic injuries, for which the use of indirect signs is essential.

Systolic prospectively ECG-triggered dual-source CT angiography for evaluation of the coronary arteries in heart transplant recipients.

OBJECTIVES: To assess feasibility, image quality, and radiation dose of prospectively ECG-triggered coronary CT angiography (CTA) in orthotopic heart transplant (OHT) recipients. METHODS: 47 consecutive OHT recipients (40 men, mean age 62.1 ± 10.9 years, mean heart rate 86.3 ± 14.4 bpm) underwent dual-source CTA to rule out coronary allograft vasculopathy in a prospectively ECG-triggered mode with data acquisition during 35% to 45% of the cardiac cycle. Two independent observers blindly assessed image quality on a per-segment and per-vessel basis using a four-point scale (1-excellent, 4-not evaluable). Scores 1-3 were considered acceptable for diagnosis. Multivariate analysis was performed to evaluate differences between image quality scores obtained at different reconstruction intervals. Effective radiation doses were calculated. RESULTS: 671 coronary segments were evaluated. Interobserver agreement on the image quality was κ=0.75. Diagnostic image quality was observed in 93.9%, 95.5% and 93.3% of the segments at 35%, 40% and 45% reconstruction intervals. Mean image quality score was 1.5 ± 0.7 for the entire coronary tree, 1.4 ± 0.7 for the RCA, 1.6 ± 0.8 for the LCA and 1.6 ± 0.7 for the Cx at the best reconstruction interval. Estimated mean radiation dose was 4.5 ± 1.2 mSv. CONCLUSION: Systolic prospectively ECG-triggered CTA allows diagnostic image quality coronary angiograms in OHT recipients at low radiation doses.

Estudio in vitro de la resistencia a la tracción de postes de fibra de vidrio cementados con cuatro agentes cementantes / In vitro study of push-out resistance of glass-fiber posts cemented with four luting agents

Introducción: La causa más frecuente de fracaso de los pernos de fibra es el desprendimiento, debido a una falla de la adhesión en la interface dentina/agente cementante. Objetivo: El objetivo de este estudio in vitro fue medir y comparar la resistencia a la tracción necesaria para producir la dislocación de postes de fibra de vidrio cementados con 4 agentes cementantes. Materiales y métodos: Las coronas de 40 caninos sanos, fueron seccionadas transversalmente a nivel del techo cameral. Tras realizar el tratamiento endodóntico, los especímenes fueron mantenidos a 80% de humedad, a 37° C por 72 horas. Aleatoriamente se distribuyeron en 4 grupos (n =10). Cada grupo recibió un poste de fibra de vidrio cementados con: Panavia F 2.0, Unicem, Fuji plus, Variolink. La cementación fue según indicaciones del fabricante y bajo presión digital, posteriormente se aplicó una carga estandarizada de 5 kilos por 5 minutos. Se efectuó una prueba de tracción utilizando una máquina de prueba universal con velocidad de 0,5 mm/min hasta el descementado. A los datos se aplicó un diseño de Análisis de Varianza, ANOVA una Víay el test de Tukey (p<0,05).Resultados: El coeficiente de determinación (R2) del modelo fue igual a un 88%. La ANOVA mostró que al menos en uno de los cementos la media de la fuerza de tracción fue significativamente distinta a las demás(p<0,0001). Al comparar las medias de la fuerzas de tracción se obtuvo diferencias estadísticamente significativas entre los 4 agentes cementantes (p<0,05).Este estudio in vitro demostró que el cemento de resina de curado-dual Panavia F 2.0 presentó la fuerza de tracción más alta. Por lo que en clínica se comportaría dentro de niveles muy aceptables (AU)

Introduction: The most frequent cause of the glass-fiber post failure was push-out due to a failure in the adhesion dentin/agent cement interface. Purpose. The purpose of this in vitro study was to evaluate and compare the dislocation resistance of glass fiber post cemented by 4 different cement agents. Material and methods. Forty extracted canine were transversal sectioned at roof pulp level (n=10). Each group received fiber posts were randomly cemented using cement Panavia F 2.0, Unicem, Fuji plus, Variolink. Each sample was loaded in tension in an Instrom universal testing machine. The maximum force required to dislodge each post was recorded. Data were subjected to 1-way ANOVA and Tukey tests. (p<0.05).Results. The determination coefficient (R2) of the model was 80%. The one-way ANOVA disclosed significant differences between groups (p<0.0001), and a multiple comparisons test revealed that statistically significant difference among the 4 cementing agents (p<0.05).Conclusions. This in vitro study demonstrated that dual-cured resin cement Panavia F 2.0 resulted in the highest dislodgement force thus would be within the clinically acceptable standard (AU)

Giant left atrial thrombus 17 years after orthotopic heart transplantation.

We present the case of a 66-year-old woman who underwent orthotopic heart transplantation 17 years earlier for dilated cardiomyopathy. After 7 years allograft coronary vasculopathy developed requiring coronary artery angioplasty. In year 15 postoperatively she experienced congestive heart failure and she became symptomatic requiring diuretics and digoxin treatment. In year 16 postoperatively a routine coronary computed tomography (CT) angiography study revealed a giant thrombus in the left atrium. The patient had had no thromboembolic-related symptoms. Anticoagulation therapy was introduced and the patient has not presented any thromboembolic-related complication. As the symptoms of cardiac insufficiency worsened we decided to evaluate the patient for re-transplantation.

Significant decline in the tuberculosis burden in the Philippines ten years after initiating DOTS.

BACKGROUND: The Philippines ranks ninth among the 22 high-burden countries for tuberculosis (TB). OBJECTIVE: To measure the burden of pulmonary tuberculosis (PTB) in the Philippines and determine the impact of the DOTS strategy. MATERIALS AND METHODS: The 2007 nationwide TB prevalence survey covered 50 clusters selected by multi-stage stratified random sampling from Metro Manila and other urban and rural areas. Subjects aged >or=10 years were screened radiographically for PTB to identify subjects for sputum examination and determine the prevalence of bacteriologically confirmed PTB, i.e., smear- and/or culture-positive PTB. RESULTS: In subjects aged >or=10 years, the 2007 prevalence of radiographic PTB was 6.3% (95%CI 5.5-7.1), bacteriologically confirmed PTB was 6.6 per 1000 (95%CI 5.1-8.1) and sputum smear-positive PTB was 2.6/1000 (95%CI 1.7-3.6). For the total population, the corresponding estimates were respectively 4.7%, 4.9/1000 and 2.0/1000. Between 1997 and 2007, there was a 31% reduction in bacteriologically confirmed PTB (P < 0.02) and a 27% reduction in smear-positive PTB (P = 0.18). This decline occurred despite the increasing poverty in the population. CONCLUSION: The survey demonstrated a significant decline in the TB burden 10 years after the implementation of DOTS, facilitated by a strategic public-private partnership.

Long-term results of ascending aorta-abdominal aorta extra-anatomic bypass for recoarctation in adults with 27-year follow-up.

OBJECTIVE: The surgical treatment of recurrent coarctation in adults supposes a redo left thoracotomy with adhesions and high risk of bleeding and injury of adjacent nerves. The rate of paraplegia in these cases may reach 2.6%. Extra-anatomic aortic bypass avoids these complications. We present our results with ascending-to-abdominal aorta extra-anatomic bypass for recurrent aortic coarctation in adults. METHODS: Between September 1979 and November 2006 12 patients underwent ascending-to-abdominal aorta bypass. There were 10 males and 2 females. Mean age was 36.2+/-11.3 (range 21-57) years old. Mean age at primary repair was 14.3+/-4.2 years old (range 8-21). Operative technique consisted of performing an ascending-to-abdominal aorta bypass via median sternotomy extended into the epigastrium with a supra-umbilical laparotomy through the mid-line abdominal fascia. Concomitant procedures were performed in six patients: three isolated aortic valve replacements (AVR), two ascending aorta graft replacements and one AVR associated with coronary artery bypass graft (CABG). RESULTS: No postoperative mortality was observed. Mean follow-up time was 10.4+/-9.3 years (range 0.3-27.8). No patients had any graft-related complication or death and all grafts were patent at the end of the follow-up. One patient developed a dilated myocardiopathy, dying at 14 years of follow-up. Four patients had persistence of arterial hypertension controlled with one drug therapy and five patients were asymptomatic. CONCLUSIONS: Ascending-to-abdominal aorta extra-anatomic bypass is a safe, effective and less invasive technique for aortic recoarctation in adults with good results at long-term.

Allergic rhinitis, feeding and oral habits, toothbrushing and socioeconomic status. Effects on development of dental caries in primary dentition.

The aim was to determine the effect of feeding and oral habits, toothbrushing, socioeconomic status and allergic rhinitis on the development of dental caries in primary dentition. In a cross-sectional study, data were obtained by means of a structured questionnaire on 1,160 children, 4-5 years old (mean = 4.5 +/- 0.5) and born in 1999, 2000 or 2001. The children also had a physical examination by an allergist and dentists. Dental caries was diagnosed according to WHO criteria. Caries experience was measured as number of deft and defs. Logistic regression analysis assessed the association between dental caries and independent variables. The dental caries prevalence was 17.9%, 28.8% of the children had allergic rhinitis symptoms, digit sucking was reported by 9.8% and pacifier use by 13.6% of the children. The mean number of deft of the sample was 1.02 (SD = 2.37) and that of defs was 1.33 (SD = 3.54). Analysis showed that breast-feeding for >12 months (p < 0.01), toothbrushing frequency (p < 0.01), sugar consumption (p < 0.01) and pacifier use (p < 0.01) each had a significant association with dental caries occurrence in primary dentition. Children with pacifier use and allergic rhinitis had more than double the risk of dental caries development. Allergic rhinitis alone has no effect on dental caries. Healthcare professionals attempting to limit dental caries should consider the effect of prolonged breast-feeding, sugary product consumption between meals and nonnutritive habits on dental caries.

Congenital bilateral coronary artery to pulmonary artery fistulas associated with left main trunk stenosis.

A rare case of a 57-year-old patient who presented with an acute coronary syndrome with incidental discovery of bilateral coronary arteriovenous fistulas originating from both coronary arteries to the pulmonary artery trunk and coronary artery atherosclerosis.

High-power ultrasound in olive paste pretreatment. Effect on process yield and virgin olive oil characteristics.

The effect of high-power ultrasound on olive paste, on laboratory thermo-mixing operations for virgin olive oil extraction, has been studied. Direct sonication by an ultrasound probe horn (105 W cm(-2) and 24 kHz) and indirect sonication with an ultrasound-cleaning bath (150 W and 25 kHz) were applied and their effects compared with the conventional thermal treatment. A quick-heating of olive paste, from ambient (12-20 degrees C) to optimal temperature conditions (28-30 degrees C), and an oil extractability improvement were observed when applying sonication. Better extractability was obtained by direct sonication for high moisture olives (>50%) whereas indirect sonication gave greater extractability for low moisture olive fruits (<50%). Optimal application of ultrasound was achieved with direct sonication for 4 min at the beginning of paste malaxation and with indirect sonication during the malaxation time. Effect of high-power ultrasound on oil quality parameters and nutritional and sensory characteristics were studied. Changes in quality parameters (free acidity value, peroxide value, K270 and K232) were not found, however significant effects on the levels of bitterness, polyphenols, tocopherols (vitamin E), chlorophyll and carotenoids were observed. Oils from sonicated pastes showed lower bitterness and higher content of tocopherols, chlorophylls and carotenoids. Related to sensory characteristics, off-flavour volatiles were not detected in oils from sonication treatments. Total peak areas of volatiles and the ratio hexanal/E-2-hexenal, as determined by SPME analysis, were lower than non-sonicated reference oils; sensory evaluation by panel test showed higher intensity of positive attributes and lesser of negative characteristics than those untreated.

Cardiac surgery in nonagenarians: hospital mortality and long-term follow-up.

Nonagenarians represent a growing part of the population. However, it is assumed that they present a poorer functional class to cope with the stress inferred by surgical interventions. The aim of this study was to review our experience with nonagenarians concerning postoperative morbidities, mortality, and long-term survival status. Retrospective data from 30 consecutive nonagenarians who underwent cardiac surgery between January 1990 and December 2002, and their long-term follow-up was analysed. There were 18 women (60%) and 11 men. Left ventricle ejection fraction (LVEF) was 50.3+/-10.5%. Fifty percent of the patients were in NYHA functional class III or IV. There were nine coronary artery bypass grafting (CABG) procedures (30%), 16 aortic valve replacements (AVR), (53%), one double valve procedure and one replacement of infected intracavitary pace-maker leads. In-hospital mortality rate was 20% (6/30). Mean follow-up was 21.5+/-19 months (r: 2.2 to 68). Actuarial survival rate at 12, 24 and 60 months was 67%, 43% and 30%, respectively. Surviving patients referred quality of life as good, all but one were in NYHA functional class I. Nonagenarians undergoing cardiac surgery have higher mortality and morbidity rates than younger patients. However, in a carefully selected group of patients, the operative risk remains acceptable.

Application of solid-phase microextraction to the analysis of volatile compounds in virgin olive oils.

Solid-phase microextraction was used as a technique for headspace sampling of extra virgin olive oil and virgin olive oil samples with different off-flavours. A 100 microm coated polydimethylsiloxane fiber was used to extract volatile aldehydes, the sampling temperature was 45 degrees C and the fiber has been exposed to the headspace for 15 min. Nonanal and 2-decenal were present in all the olive oils with extraction off-flavours but were not in extra virgin olive oil sample.

Tuberculosis infection and disease in children living in households of Filipino patients with tuberculosis: a preliminary report.

SETTING: DOTS Clinic with a DOTS-Plus pilot project for the management of multidrug-resistant tuberculosis (MDR-TB) in a high burden country. OBJECTIVE: To determine the prevalence of tuberculosis (TB) infection and disease among pediatric household contacts of patients with pulmonary TB (PTB). DESIGN: Cross-sectional study. METHODOLOGY: One hundred and fifty-three children aged 0-15 years in the households of 62 bacteriologically confirmed PTB patients, including 44 with MDR-TB, were studied. BCG scars were noted, and tuberculin skin test (TST), screening chest radiography, and sputum or gastric aspirate smear and culture for Mycobacterium tuberculosis in those with radiographic findings suggestive of PTB were done. RESULTS: For children in this study, the prevalences of latent TB infection (LTBI), radiographically diagnosed pulmonary TB, and bacillary pulmonary TB were 69.2%, 3.3%, and 0.65%, respectively. Only age > or = 5 years was found to be a significant predictor of LTBI (OR 3.17, 95%CI 1.43-7.01). CONCLUSION: Contact investigation for active case-finding and early treatment of TB in children from households of patients with active PTB is essential for TB control. Further study on a more precise definition of TB infection and strategies for control in this population will be pursued.

Dermatología basada en evidencias / Evidence-based Dermatology

Se presenta una revisión de medicina basada en Evidencias (MBE) aplicándola a la Dermatología, resumiendo en forma práctica los pasos para su aplicación tales como, la identificación del problema clínico más relevante de un paciente, la búsqueda de toda la evidencia disponible sobre el tema, la valoración crítica de toda la literatura encontrada y finalmente la aplicación de la evidencia encontrada a la práctica según nuestra propia experiencia. Además, se hace mención de las razones que justifican su uso así como sus principales limitaciones. Se incluye un glosario con los principales términos de interés y entre paréntesis la traducción al inglés. Palabras claves: Dermatología basada en evidencias, medicina basada en evidencias.

Tuberculosis in the urban poor settlements in the Philippines.

SETTING: Urban poor settlements in the Philippines. OBJECTIVE: To determine the magnitude of the tuberculosis problem in urban poor settlements in comparison with urban areas studied in the Nationwide Tuberculosis Prevalence Survey. STUDY DESIGN AND METHOD: A multistage cluster survey of BCG scar, tuberculin test, chest radiography and sputum examination for bacillary disease, in urban poor areas. RESULTS: The prevalences of culture-positive and smear-positive tuberculosis were 17.5 +/- 2.3 (95% CI 13.3-22.4) and 7.9 +/- 2.3 per thousand (95% CI 2.611.5), respectively. Extrapolated to the total population, the rates in the urban poor settlements were 12.4 +/- 1.7 (95% CI 9.6-16.2) and 5.6 +/- 1.6 per thousand population (95% CI 1.3-8.3), respectively. The prevalence of active pulmonary tuberculosis in subjects aged 10 years or more was 66 +/- 5.6/1000 (95% CI 55-77). The BCG vaccination rate was 72%. The overall prevalence of tuberculosis infection was 66%, and 39% in those aged 5-9 years, corresponding to an annual risk of infection (ARI) of 6.5%. CONCLUSION: The problem of tuberculosis was substantial in the urban poor settlements, and was appreciably worse than that in the general urban population.

[Clinical characterization of 450 patients with cerebrovascular disease admitted to a public hospital during 1997]. / Caracterización clínica de 450 pacientes con enfermedad cerebrovascular ingresados a un hospital público durante 1997.

BACKGROUND: In Chile, cerebrovascular diseases are the fifth cause of death among men and the third cause among women. AIM: To assess the clinical features and management of patients with cerebrovascular disease admitted to a public hospital during 1997. PATIENTS AND METHODS: A retrospective analysis of clinical records of patients discharged with a diagnosis of cerebrovascular disease. Those records in which there was discordance between the discharge diagnosis and the clinical picture were not considered in the analysis. RESULTS: Of the 563 discharges from the hospital with the diagnosis of cerebrovascular disease, 487 records were located and 450 were considered in the analysis. Fifty four percent of patients were male and ages ranged from 17 to 96 years old. Fifty-one percent of patients had an ischemic stroke, 34% a cerebral hemorrhage, 12% a subarachnoidal hemorrhage and 3% a transient ischemic attack. There was a history of hypertension in 64% patients and 20% had an adequate treatment. Eighteen percent were diabetics, 34% had a heart disease and 20% had a previous episode of stroke. Mean hospital stay was 6.3 days in the emergency room and 11 days in the neurology ward. Hospital infections appeared in 21% of patients (respiratory in 68% and urinary in 22%), lethality was 30.5% and a CAT scan was done in 94%. At the moment of admission, 10% of patients had an evolution of less than 2 hours, 27% had an evolution between 2 and 6 hours and nine cases were potential eligible for thrombolysis. CONCLUSION: This is a picture of the local features of patients with cerebrovascular diseases that can be used as a reference for future studies.

Low-cholesterol and high-fat diets reduce atherosclerotic lesion development in ApoE-knockout mice.

We have investigated the effect of most common oils used in human nutrition on the development of atherosclerosis in apoE-knockout mice. Seven groups of animals, separated according to sex, were fed for 10 weeks either chow diet or the chow diet 10% (wt/wt) enriched with different oils (palm, coconut, 2 types of olive oil, and 2 types of sunflower oil) without addition of cholesterol. At the end of this period, plasma lipid parameters were measured and vascular lesions scored. None of the diets induced changes in plasma cholesterol concentrations, whereas plasma triglycerides were uniformly reduced in all diet groups. Some diets caused significant reductions in the size of atherosclerotic lesions in males and others in females; males responded most to sunflower oils and females to palm oil and one olive oil (II). The lesion reduction in males consuming sunflower oils was associated with the decrease of triglycerides in triglyceride-rich lipoproteins, whereas the decrease in females consuming olive oil II or palm oil was accompanied by an increase in plasma apoA-I. The increase in plasma apoA-I in the latter condition, is mainly due to overexpression of hepatic message elicited by a mechanism independent of apoE ligand. The data suggest that the different diets modulate lesion development in a gender specific manner and by different mechanisms and that the development of atherosclerosis, due to genetic deficiencies, may be modulated by nutritional maneuvers that may be implemented in human nutrition.

The 1997 Nationwide Tuberculosis Prevalence Survey in the Philippines.

SETTING: The Philippines is a developing country where tuberculosis (TB) remains a significant public health problem. OBJECTIVE: To determine the prevalence of TB as a basis for setting the targets of the National Tuberculosis Control Program. STUDY POPULATION AND METHODS: A multi-stage cluster survey of a random sample of 21960 subjects from 36 clusters nationwide was undertaken from 2 April to 31 July 1997. BCG scar verification and tuberculin testing was performed for subjects aged 2 months and over, and chest radiography screening was done on subjects 10 years and older. Sputum samples were collected from individuals who were initially assessed to have abnormal chest radiographs to determine the prevalence of bacillary tuberculosis. Acid-fast smear by modified Kinyoun's technique and culture on Löwenstein Jensen were done to demonstrate Mycobacterium tuberculosis. RESULTS: The prevalence of active pulmonary TB was 42/1000 population. The prevalence of culture-positive and smear-positive cases was 8.1 and 3.1/1000, respectively. The prevalence was similar in urban and rural areas. CONCLUSION: Morbidity from TB remains high. Allowing for methodological differences from the survey in 1981-1983, the prevalence of active pulmonary TB was unchanged. There was only a minimal decrease, of 37% for smear-positive cases and 25% for culture-positive cases, in the 14-year interval.

Internet e infección por VIH/SIDA / Internet and HIV infection and AIDS

La infección por VIH y el SIDA constituyen en un flagelo que afecta a todo el mundo lo que se refleja en la gran cantidad de información que, sobre el tema, es posible obtener a través de Internet, desde páginas dirigidas a grupos de riesgo hasta las más sofisticadas publicaciones científicas. Debido a la diversidad de información que las instituciones publican en Internet, las páginas web han sido clasificadas según su contenido, citándose las de mayor popularidad.