Resumen Antecedentes: Los almacenes de carbono (C) de los bosques del mundo ascienden a 861 Pg; 44 % se encuentra en el suelo. A pesar de su importancia como reservorio, los estudios sobre carbono orgánico en el suelo (COS) en los bosques de México son escasos. Pregunta: ¿El carbono orgánico en el suelo varía entre tipos de vegetación y tipos de suelo en los bosques de Durango? Sitio de estudio: Bosques templados de Durango, México. Métodos: Los datos de COS se obtuvieron de 399 sitios permanentes. Se colectaron muestras de hojarasca, horizonte de fermentación y de las capas de suelo de 0-30 y 30-60 cm. Los contenidos de C se determinaron en un analizador elemental. El cálculo de las incertidumbres se realizó siguiendo los procedimientos usados por la Comisión Nacional Forestal. Resultados: El COS promedio estimado fue 8.48, 1.08, 110.62 y 53.44 Mg ha-1 en hojarasca, horizonte de fermentación, suelo de 0-30 y de 30-60 cm, respectivamente. Los almacenes promedio de C total en el suelo oscilaron desde 26.34 hasta 578.27 Mg ha-1 (incertidumbre: 6.31 %). La mayor variabilidad de los almacenes de COS se presentó en el bosque de pino. Conclusiones: El tipo de bosque no influye en los almacenes de carbono orgánico en el suelo, pero sí el tipo de suelo. Los reservorios de COS en los bosques Durango son más altos comparados con el mismo tipo de vegetación en otras regiones del país.

Abstract Background: Carbon (C) stocks in the world's forests amount to 861 Pg; 44 % is in the soil. Despite its importance as a reservoir, studies on soil organic carbon (SOC) in forests of Mexico are scarce. Questions: Does soil organic carbon vary between vegetation types and soil types in Durango forests? Study site: Temperate forests of Durango, Mexico. Methods: SOC data were obtained from 399 permanent sites. Samples were collected from leaf litter, fermentation horizon and from the 0-30 and 30-60 cm soil layers. C contents were determined on an elemental analyzer. Uncertainties were calculated following the procedures used by the National Forestry Commission. Results: The average SOC was 8.48, 1.08, 110.62 and 53.44 Mg ha-1 in litter, fermentation horizon, 0-30 and 30-60 cm soil, respectively. The average total soil C stocks ranged from 26.34 to 578.27 Mg ha-1 (uncertainty: 6.31 %). The greatest variability of SOC stocks occurred in pine forest. Conclusions: Forest type does not influence soil organic carbon pools, but soil type does. SOC pools in Durango forests are higher compared to the same type of vegetation in other regions of the country.

Resumen Una mayor diversidad de forrajes en otoño-invierno incrementa la entrada de carbono (C) y nitrógeno (N) al suelo en los residuos de cosecha. El objetivo del estudio fue evaluar el aporte potencial de C y N al suelo en los residuos de forrajes alternativos y tradicionales durante el ciclo otoño-invierno. En el experimento se evaluó el rendimiento de materia seca (MS), cantidad de residuos y la relación C/N en 11 especies forrajeras. Los cultivos tradicionales avena, cebada, triticale, trigo, trébol Alejandrino y ballico anual aportaron menor cantidad de residuos de cosecha (365 a 612 kg ha-1) y de menor calidad con valores de la relación C/N de 23.5 a 42.8. Los cultivos alternativos canola, remolacha, brásicas, rábano y garbanzo aportaron mayor cantidad de residuos (432 a 2 958 kg ha-1), con mayores contenidos de N (18.5 a 32.6 g kg-1) y menores valores de la relación C/N (11.4 a 20). Los cultivos alternativos con raíces engrosadas como remolacha, brásicas y rábano mejoraron la cantidad y calidad de aportación de residuos de cosecha, con una capacidad potencial de captura de C similar a los cultivos tradicionales. Sin embargo, sólo la brásica Winfred y el rábano Graza obtuvieron rendimientos de MS (10 094 a 11 636 kg ha-1) similares o mayores a los observados en los cereales testigo avena Cuauhtémoc (11 161 kg ha-1) y triticale AN105 (9 644 kg ha-1). Una mayor diversidad de forrajes puede mejorar en cantidad y calidad la aportación de residuos de cosecha al suelo.

Abstract A greater diversity of forages in autumn-winter increases the input of carbon (C) and nitrogen (N) into the soil in the harvest residues. The objective of the study was to evaluate the potential contribution of C and N to the soil in alternative and traditional forage residues during the autumn-winter cycle. The experiment evaluated the dry matter (DM) yield, quantity of residues and C/N ratio in 11 forage species. The traditional crops oats, barley, triticale, wheat, berseem clover and annual ryegrass contributed less harvest residues (365 to 612 kg ha-1) and of lower quality, with values of the C/N ratio of 23.5 to 42.8. Alternative crops canola, beet, brassicas, radish and chickpea contributed more residues (432 to 2 958 kg ha-1), with higher N contents (18.5 to 32.6 g kg-1) and lower values of the C/N ratio (11.4 to 20). Alternative crops with thickened roots such as beet, brassica and radish improved the quantity and quality of harvest residue contribution, with a potential C capture capacity similar to traditional crops. However, only Winfred brassica and Graza radish obtained DM yields (10 094 to 11 636 kg ha-1) similar to or greater than those observed in the control cereals Cuauhtémoc oats (11 161 kg ha-1) and AN105 triticale (9 644 kg ha-1). A greater diversity of forages can improve in quantity and quality the contribution of harvest residues to the soil.

Resumen Antecedentes: actualmente existe un creciente interés en investigar métodos que logren disminuir el dolor muscular de inicio retardado. Se ha postulado que antioxidantes como las vitaminas C y E pueden atenuarlo. Objetivo: evaluar la efectividad de vitamina E en la atenuación del dolor muscular de inicio retardado. Materiales y métodos: se realizó una búsqueda bibliográfica en las bases de datos Medline, Registro Central Cochrane, Scopus, SportDiscus y SciELO, utilizando los términos: “vitamin e supplementation”, “muscle damage” y “delayed onset muscle soreness”. Resultados: se revisaron estudios en diversos grupos poblacionales, con diferentes métodos de evaluación y diversas dosis de vitamina E. Los resultados obtenidos fueron controversiales, en algunos casos se demostró un efecto atenuante del dolor muscular de inicio retardado y en otros casos no. Conclusiones: la vitamina E produce una disminución del estrés oxidativo y estabilización el sarcolema; no obstante, faltan pruebas concluyentes para afirmar que la vitamina E tenga el efecto de generar mejoras en los biomarcadores asociados al dolor muscular de inicio retardado.

Abstract Background: Currently, there is a growing interest in investigating methods that reduce delayed onset muscle pain. It has been postulated that antioxidants such as vitamin C and E can attenuate it. Objective: To evaluate the effectiveness of vitamin E in mitigating delayed onset muscle pain. Materials and Methods: A bibliographic search was carried out in the following databases: Medline, Registry Central Cochrane, Scopus, SportDiscus and SciELO, using the terms: “vitamin e supplementation”, “muscle damage” and “delayed onset muscle soreness”. Results: Studies in diverse population groups were reviewed, with various evaluation methods and differing doses of vitamin E. The results were very controversial, in some cases a delayed onset pain effect was demonstrated and in other cases not. Conclusion: Vitamin E produces a decrease in oxidative stress and stabilization of sarcolemma, however, conclusive evidence is lacking to state that vitamin E will have the effect of generating improvements in biomarkers associated with delayed onset muscle pain.

BACKGROUND: Public health facilities are used by the majority of South Africans, and healthcare utilisation surveys have been a useful tool to estimate the burden of disease in a given areaOBJECTIVES: To describe care-seeking behaviour in a periurban site with a high prevalence of HIV infection, as well as barriers to seeking appropriate healthcareMETHODS: We conducted a cross-sectional household survey in 22 wards of the Msunduzi municipality in KwaZulu-Natal Province, South Africa, from October to December 2013 using a simple random sample of households selected from a 2011 census enumeration. A primary caregiver/adult decision-maker was interviewed regarding demographic data as well as health status and recent self-reported episodes of selected illnesses and healthcare utilisationRESULTS: Of the 2 238 eligible premises visited, 1 936 households (87%) with a total of 9 733 members were enrolled in the study. Of these, 635 (7%) reported one or more episodes of infectious illness during the study period. Public health clinics were most frequently consulted for all illnesses (361/635, 57%). Private healthcare (general practitioner, private clinic, private hospital) was sought by 90/635 of individuals (14%), only 13/635 (2%) reported seeking care from traditional healers, religious leaders or volunteers, and 71/635 (11%) did not seek any medical care for acute illnesses. Individuals in the lowest income group were more likely to seek care at public health facilities than those in the highest income group (70% v. 32%CONCLUSIONS: Public health facility-based surveillance may be representative of disease patterns in this community, although surveillance at household level shows that high-income individuals may be excluded because they were more likely to use private healthcare, and the proportion of individuals who died at home would have been missed by facility-based surveillance. Data obtained in such surveys may be useful for public health planning

BACKGROUND. Pleural effusions are a common reason for presentation to healthcare facilities. Blind closed pleural biopsy can be a useful tool to diagnose their cause, especially in resource-limited settings. OBJECTIVES. To determine the aetiology, frequency and change in profile of histopathological diagnoses made at Chris Hani Baragwanath Academic Hospital (CHBAH), Johannesburg, South Africa, over the period 1 January 2001 - 31 December 2015. METHODS. Pleural biopsies performed at CHBAH and analysed by histopathologists from the National Health Laboratory Service at the hospital over the study period were retrospectively reviewed by accessing reports from two databases (DISA and TrakCare). The subjects' ages, genders, HIV status and histopathological diagnoses as well as adenosine deaminase and Ziehl-Neelsen results were recorded. RESULTS. A total of 1 013 samples were included in the study, with 780 considered adequate for assessment. The most common diagnosis was granulomatous inflammation (48.1%, n=375), with the most common type being necrotising granulomatous inflammation (73.6%, n=276). Ten percent of biopsies (n=78) showed malignancy, most commonly adenocarcinoma, with 46.2% (n=36) metastatic and 23.1% (n=18) primary lung adenocarcinoma. The odds of being diagnosed with malignancy showed increasing statistical significance above the age of 40 years: 40 - 49 years odds ratio (OR) 8.7, 95% confidence interval (CI) 1.1 - 66.9 (p=0.038); 50 - 59 years OR 12.4, 95% CI 1.6 - 95.0 (p=0.015); >60 years OR 23.0, 95% CI 3.1 - 171.3 (p=0.002). HIV seropositivity was associated with lower odds of being diagnosed with malignancy compared with HIV-negative patients (OR 0.5, 95% CI 0.2 - 0.9; p=0.040), with greater odds of a 'non-cancer' diagnosis in HIV-positive patients (including granulomatous inflammation and pleuritis (OR 2.16, 95% CI 1.03 - 4.51; p=0.040)). CONCLUSIONS. Blind closed pleural biopsy has a role to play in the diagnosis of exudative pleural effusions in resource-limited settings, particularly for patients suspected to have tuberculosis (TB) or malignancy. TB remains a common cause of exudative pleural effusions. Patients aged >40 years presenting with an exudative pleural effusion should routinely have pleural biopsy performed. However, this study showed a high frequency of inadequate specimens from closed pleural biopsy. Training in the performance of this procedure to increase diagnostic rates is recommended.

Abstract: Introduction: Cervical spine involvement is common in patients with RA, risk factors such as disease activity may be related to asymptomatic cervical instability. Objective: To determine the associated factors for asymptomatic cervical spine instability in patients with rheumatoid arthritis. Material and methods: Case and control study from the external spine and rheumatology consultation of a level II trauma center to identify all patients diagnosed with rheumatoid arthritis (RA) and asymptomatic cervical instability. With simple X-rays of the cervical spine, carrying out radiographic measurements, the diagnosis of cervical instability was performed, risk factors such as the presence of rheumatoid factor (FR), previous articular surgeries, elevations of the C-reactive protein (PCR) values were evaluated. The severity and activity of the disease measured in the activity index of 28 articulations (DAS 28) in addition to the index of activity of the simplified disease (SDAI). Results: We assessed 32 patients, nine patients (28.1%) met the criteria for instability of the anterior cervical spine atlantoaxial subluxation (SAAa) (100%), also one patient with SAAa presented vertical subluxation (SV), risk factors more relevant: DAS 28 with an OR = 3.54, SDA with an OR = 2.34 and finally the PCR > 1.0 its OR = 2.88. Conclusion: The risk factors associated opportunely in our population are the severity of the activity of the disease that we can see in the DAS and SDAI when applied in patients and PCR > 1.0.

Resumen: Introducción: La afectación de la columna cervical es común en pacientes con artritis reumatoide (AR), factores de riesgo como la actividad de la enfermedad puede estar relacionada con inestabilidad cervical asintomática. Objetivo: Determinar los factores asociados a la inestabilidad de la columna cervical asintomáticos en pacientes con artritis reumatoide. Material y métodos: Estudio de casos y controles provenientes de la consulta externa de reumatología y columna de un centro de trauma de nivel II para identificar a todos los pacientes diagnosticados con AR e inestabilidad cervical asintomáticos. Con radiografías simples de la columna cervical que hacen mediciones radiográficas, se realizó el diagnóstico de inestabilidad cervical, se evaluaron los factores de riesgo como la presencia de factor reumatoide (FR), cirugías articulares previas, las elevaciones de los valores de proteína C reactiva (PCR), la severidad y actividad de la enfermedad medida en el índice de actividad de la enfermedad de 28 articulaciones (DAS 28), además del índice de actividad de la enfermedad simplificada (SDAI). Resultados: Se evaluaron 32 pacientes, nueve (28.1%) cumplieron con los criterios para inestabilidad de la columna cervical con subluxación atlantoaxial anterior (SAAa) (100%), también un paciente con SAAa presentaba subluxación vertical (SV), los factores de riesgo más relevantes: el DAS 28 con un OR = 3.54, SDA con un OR = 2.34 y por último el PCR > 1.0 su OR = 2.88. Conclusión: Los factores de riesgo asociados oportunamente en nuestra población son la severidad de la actividad de la enfermedad que podemos observar en el DAS y SDAI al aplicarlos en los pacientes y PCR > 1.0.

Abstract Forest fuels play an important role in the field of global warming, therefore a proper estimation will allow a decrease of the uncertainty levels of carbon (C) contents. This paper describes the evaluation process for loads of duff (litter and fermentation layer, M) and downed woody material (MLC). A summary of the C content reported in Mexico is also presented. The evaluation of these fuels has been primarily based on the strategy of planar intersections. The contents of C were determined using different percentages of C content with respect to mass (dry weight), ranging from 47.5% to 66.9%, although a percentage of 50% was used, in general. Most works has been focused on temperate ecosystems, where 9.43 Mg C ha-1 of MLC was reported. While for tropical forests there was 8 Mg C ha-1. For M was reported 6.91 Mg C ha-1 and 4.25 Mg C ha-1 in duff, and 5.88 Mg C ha-1 and 1.39 Mg C ha-1 in the fermentation layer for temperate regions and tropical forests, respectively. It is concluded that there is little information on C evaluations regarding M and MLC. In addition, other regions should be considered and standardized evaluation procedures should be used. In this way, the information generated will be comparable and compatible. This will not only reduce levels of uncertainty, but also present information at different scales.

Resumen Los combustibles forestales juegan un papel importante en el ámbito del calentamiento global, por lo que la adecuada estimación de las camas de combustible permitirá disminuir los niveles de incertidumbre de los contenidos de carbono (C) de los ecosistemas forestales. Este trabajo describe los procesos de evaluación de las cargas de mantillo (hojarasca y capa de fermentación, M) y de material leñoso caído (MLC); además, presenta una síntesis de los contenidos de C registrados en México. La evaluación de M y MLC se basó principalmente en la estrategia de intersecciones planares. Los contenidos de C se determinaron usando diferentes porcentajes de contenido de C respecto a la masa (peso seco), que variaron desde 47.5% hasta 66.9% aunque, en general, se consideró 50%. La mayoría de trabajos revisados se enfocaron en ecosistemas de regiones templadas, con registros de 9.43 Mg C ha-1 de MLC, mientras que para selvas se registraron 8 Mg C ha-1. En cuanto a M, se observó 6.91 Mg C ha-1 y 4.25 Mg C ha-1 en la capa de hojarasca y 5.88 Mg C ha-1 y 1.39 Mg C ha-1 en la capa de fermentación para regiones templadas y selvas, respectivamente. Se encontró muy poca información sobre las evaluaciones de C correspondientes a M y MLC, la mayoría enfocada a ecosistemas templados y tropicales, por lo que se resalta la necesidad de considerar otras regiones climáticas. Las evaluaciones de las cargas de los combustibles forestales deben hacerse en forma estandarizada y con protocolos comunes, de tal forma que la información generada pueda ser tanto comparable como compatible. Esto permitirá reducir los niveles de incertidumbre y presentar la información en diferentes escalas. De esta manera, será posible no solo reducir los niveles de incertidumbre, sino también escalar la información.

A descriptive and cross sectional study of 253 patients under 5 years of age, admitted with the diagnosis of acute respiratory infections in the District Hospital of Sayaxché, was carried out from January to September, 2012, with the aim of characterizing morbidity. Male sex (55.7%), children under 1 year (55.3%), exposure to passive smoke as main associated risk factor (75%), fever as clinical manifestation at admission (98%) prevailed in the series, as well as pneumonia/bronchopneumonia in this same age group (88.6%), of which 58.7% received treatment with ceftriaxone. The hospital stay was 4-6 days and most of the patients affected were better at discharge

Se realizó un estudio descriptivo y transversal de 253 pacientes menores de 5 años de edad, ingresados con diagnóstico de infecciones respiratorias agudas en el Hospital Distrital de Sayaxché, desde enero a septiembre de 2012, con vistas a caracterizar la morbilidad. En la serie predominaron el sexo masculino (55,7 %), los niños menores de 1 año (55,3 %), la exposición al humo pasivo como principal factor de riesgo asociado (75 %), la fiebre como manifestación clínica al ingreso (98 %), así como la neumonía/bronconeumonía en este mismo grupo de edades (88,6 %), de los cuales 58,7% recibió tratamiento con ceftriaxone. La estadía hospitalaria fue generalmente de 4 a 6 días y la mayoría de los afectados egresaron mejorados

INTRODUCTION:Survival of patients with acquired immune deficiency syndrome has improved with combination antiretroviral therapy; mortality due to liver diseases, however, has also increased in these patients.OBJECTIVES:To estimate the accumulated probability of survival in human immunodeficiency virus-hepatitis C virus coinfected and non-coinfected patients and to investigate factors related to acquired immune deficiency syndrome patients' survival.METHODS:Non-concurrent cohort study using data from surveillance information systems of acquired immune deficiency syndrome patients over 13 years of age. Hepatitis C and B, human immunodeficiency virus exposure category, CD4+ T cell count, age group, schooling, race, sex, and four acquired immune deficiency syndrome diagnosis periods were studied. Kaplan-Meier survival analysis and Cox model with estimates of the hazard ratio and 95% confidence interval were used.RESULTS:Of the total 2864 individuals included, with median age was 35 years, 219 died (7.5%), and 358 (12.5%) were human immunodeficiency virus-hepatitis C virus coinfected. The accumulated probability of survival in human immunodeficiency virus-hepatitis C virus coinfected patients, after acquired immune deficiency syndrome diagnosis, at 120 months, was 0%, 38.9%, 83.8% in 1986-1993, 1994-1996, 1997-2002, respectively, and 92.8% at 96 months in 2003-2010; survival in non-coinfected patients at 120 months was 80%, 90.2%, 94% in 1986-1993, 1994-1996, 1997-2002, respectively, and 94.1% at 96 months in 2003-2010. In the multivariate model the following variables were predictive of death: hepatitis C virus coinfection (hazard ratio=2.7; confidence interval 2.0-3.6); Hepatitis B virus coinfection (hazard ratio=2.4; confidence interval 1.7-3.6); being >50 years old (hazard ratio=2.3; confidence interval 1.3-3.8); having 8-11 years of schooling (hazard ratio=1.6; confidence interval 1.1-2.3), having 4-7 years of schooling (hazard ratio=1.9; confidence interval 1.3-2.8) and having up to 3 years of schooling (hazard ratio=3.3; confidence interval 2.0-5.5).CONCLUSIONS:Among patients diagnosed after 1996, there was a significant increase in the cumulative probability of survival in human immunodeficiency virus-hepatitis C virus coinfected individuals; among those diagnosed with acquired immune deficiency syndrome from 2003 to 2010, this probability was similar between coinfected and non-coinfected patients.

A total of 63 beef offal samples (beef liver = 16; beef lung = 14; beef intestine = 9; beef tripe = 15; beef spleen = 9) from three wet markets (A, B, and C) in Selangor, Malaysia were examined for the prevalence and microbial load of Listeria monocytogenes. A combination of the most probable number and polymerase chain reaction (MPN-PCR) method was employed in this study. It was found that L. monocytogenes detected in 33.33% of the beef offal samples. The prevalence of L. monocytogenes in beef offal purchased from wet markets A, B, and C were 22.73%, 37.50% and 41.18% respectively. The density of L. monocytogenes in all the samples ranged from<3upto> 2,400 MPN/g. The findings in this study indicate that beef offal can be a potential vehicle of foodborne listeriosis.

La impulsividad se refiere al actuar sin prudencia. Puede ser perjudicial para el funcionamiento y la interacción social, y está significativamente implicada en varias condiciones clínicas, como por ejemplo la violencia y la adicción. Evidencia para el apuntalamiento neuronal de la impulsividad de tanto la población sana como la clínica, integrada con los hallazgos de los estudios genéticos en el mismo tema, dan conocimiento importante dentro de un modelo neuro-conductual de la impulsividad. En esta revisión, la desinhibición y la decisión-acto impulsivo en el constructo de la impulsividad son abordados. Estudios conductuales y de imagen genética sobre el tema serán también revisados y discutidos. Hallazgos en estudios de neuro-imagen, estudios clínicos y estudios genéticos convergen para producir un mejor entendimiento de las diferencias individuales en el continuo. Los esfuerzos de la investigación futura deberían continuar apuntando al enfoque de asociación para identificar correlaciones neuro-conductuales relevantes parar elucidar el impacto de los genes a través de fenotipos desde neurales hasta conductuales. Estos descubrimientos potenciales, cuando son incorporados con medidas psicológicas e inmunológicas, no estarían sólo impulsando el entendimiento de la impulsividad, sino que también guían las intervenciones de desarrollo para mejorar desordenes de funcionamiento social/psicológico inadaptado apuntalados por esta.

Impulsivity refers to acting without forethought. It can be detrimental to daily social functioning and interaction, and is significantly implicated in several clinical conditions, e.g. violence and addiction. Evidence for the neural underpinnings of impulsivity from both healthy and clinical populations, integrated with the findings from genetic studies on the same topic, lend important insight into a neurobehavioral model of impulsivity. In this review, disinhibition and impulsive decision-making in the impulsivity construct are covered. Recent behavioral and imaging-genetic studies on the topic will also be reviewed and discussed. Findings from neuroimaging studies, clinical studies, and genetic studies converge to provide a better understanding of individual differences on the continuum. Future research efforts should continue to focus on the association approach to identify relevant neural-behavioral correlations in order for elucidating the impact from genes through neural to behavioral phenotypes. These potential findings, when being incorporated with physiological and immunological measures, would not only hasten understanding of impulsivity, but guide interventions development for ameliorating maladaptive social/psychological functioning disorders underpinned by it.

Acute asthma attacks (asthma exacerbations) are increasing episodes of shortness of breath, cough, wheezing or chest tightness associated with a decrease in airflow that can be quantified and monitored by measurement of lung function (peak expiratory flow (PEF) or forced expiratory volume in the 1st second) and requiring emergency room treatment or admission to hospital for acute asthma and/or systemic glucocorticosteroids for management. The goals of treatment are to relieve hypoxaemia and airflow obstruction as quickly as possible, restore lung function, and provide a suitable plan to avoid relapse. Severe exacerbations are potentially life-threatening and their treatment requires baseline assessment of severity, close monitoring, and frequent reassessment using objective measures of lung function (PEF) and oxygen saturation. Patients at high risk of asthma-related death require particular attention. First-line therapy consists of oxygen supplementation, repeated administration of inhaled short-acting bronchodilators (beta-2-agonists and ipratropium bromide), and early systemic glucocorticosteroids. Intravenous magnesium sulphate and aminophylline are second- and third-line treatment strategies, respectively, for poorly responding patients. Intensive care is indicated for severe asthma that is not responsive to first-line treatment. Antibiotics are only indicated when there are definite features of bacterial infection. Factors that precipitated the acute asthma episode should be identified and preventive measures implemented. Acute asthma is preventable with optimal control of chronic asthma.

Introduction: viral DNA levels in serum samples are a useful marker to monitor the disease progression and the treatment response in patients with chronic hepatitis B. Commercial kits for this purpose are available, but they are considerably expensive. Objectives: to evaluate the analytical performance of a real-time polymerase chain reaction (RT-PCR) assay for Hepatitis B virus DNA quantification. Methods: specific primers to the gene C and TaqMan chemistry in a LightCycler 1.5 equipment was used. A standard curve was made and evaluated. Two hundred and seventy-two serum samples were used to assess the clinical and analytical specificity, the genotypic accuracy and specificity, the intra-assay and interassay coefficients of variation and the comparison with a commercial assay and with the qualitative PCR. Results: the standard curve showed a strong linear correlation (r= -1) and low error values in the tested target DNA concentration. Analytical and clinical specificities were 100 %. Genotype accuracy and specificity showed that the differences between the results obtained by RT-PCR assay and those of the reference assay were less than 0.5 Log10. The 95% HBV DNA detection end-point assessed by Probit analysis was 16.41 IU/µL with a dynamic range of quantification of 10(8) IU/mL. Intra-assay and interassay coefficients of variation ranged from 0.16 to 1.45 % and 0.9 to 2.62 % respectively. The RT-PCR assay correlated well with those from a commercial assay (r= 0.964 and r²= 0.929) and with the HBV qualitative PCR, thus confirming its better sensitivity and advantages. Conclusions: the RT-PCR assay is well suited to monitoring HBV DNA levels showing to be sensitive, specific and reproducible. Its application in the clinical practice ensures a better diagnosis and management of patients with chronic hepatitis B in Cuba.

Introducción: los niveles de ADN viral en muestras de suero son un marcador útil para monitorear la progresión de la enfermedad y la respuesta al tratamiento en pacientes con hepatitis B crónica; de ahí que se comercialicen estuches diagnósticos para esta función, con la desventaja de ser costosos. Objetivos: desarrollar y evaluar el desempeño analítico de un sistema de reacción en cadena de la polimerasa en tiempo real para la cuantificación del ADN del virus de la hepatitis B. Métodos: se utilizaron cebadores que amplifican un fragmento del gen C y sonda de hidrólisis en el equipo LightCycler 1.5. Se construyó una curva estándar y se evaluó su eficiencia. Se utilizaron 272 muestras de suero para ensayos de especificidad analítica y clínica, especificidad y exactitud genotípica, coeficientes de variación intraensayo e interensayo, comparación con un estuche comercial y con la reacción en cadena de la polimerasa cualitativa para el virus de la hepatitis B. Resultados: la curva estándar mostró excelente correlación lineal (r= -1) y valores muy bajos de error a lo largo de varias magnitudes de concentración de ADN diana. La especificidad analítica y clínica fue de 100 %, en tanto que al evaluar la especificidad y exactitud genotípica, se obtuvo que las diferencias entre los Log10 del valor obtenido y el de referencia eran inferiores a 0,5 Log10. El límite de detección por análisis de Probit se estimó en 16,41 UI/µL con un rango dinámico de cuantificación de hasta 10(8) UI/mL. El sistema mostró bajos coeficientes de variación intraensayo (0,16 a 1,45 %) e interensayo (0,9 a 2,62 %). La comparación con el estuche comercial artus HBV LC PCR kit mostró una correlación de r= 0,964 y r²= 0,929; con la reacción en cadena de la polimerasa cualitativa se confirmó la mayor sensibilidad y ventajas de la reacción en cadena de la polimerasa en tiempo real. Conclusiones: el ensayo cumple con los requisitos para la cuantificación del ADN del virus de la hepatitis B, que demuestra ser específico, sensible y reproducible. Su aplicación permitirá un mejor diagnóstico y seguimiento de los pacientes con hepatitis B crónica en Cuba.

El objetivo del presente estudio fue identificar patógenos presentes en una sintomatología en plantas de sainillo (Dieffenbachia oerstedii) y conde (Syngonium podophyllum) en una finca bananera en Limón, Costa Rica. De febrero a noviembre del año 2007, se analizó la presencia de agentes patogénicos asociadas a una sintomatología observada en plantas tratadas o no con herbicida, en la finca Limofrut C, Matina, Limón. Se tomaron muestras y se llevaron al laboratorio de Fitopatología del Centro de Investigación en Protección de Cultivos, de la Universidad de Costa Rica. Ahí se determinó la presencia de las bacterias Pseudomonas spp y Erwinia spp asociadas a las muestras de sainillo sintomáticas y una mezcla de bacterias y Xanthomonas spp asociadas a las muestras de conde. Se detectó la presencia de bacterias Pseudomonas fluorescentes en las muestras de sainillo no sintomáticas.

The objective of this work was to analyze the presence of pathogenisc agents associated to field symptoms observed on D. oerstedii and S. podophyllum, treated with herbicides and untreated, studied from February to November of 2007, at Limofrut C banana farm, Matina, Costa Rica. Samples from symptomatic tissue of both species were taken to the laboratory. Pseudomonas spp and Erwinia spp were found on samples from D. oerstedii tissue; Xanthomonas spp were found on samples from S. podophyllum symptomatic tissue. Fluorescent Pseudomonas bacteria were detected on samples from non symptomatic D. oerstedii tissue.