Silvia Ruiz-Velasco

Prevalencia de asma, rinitis y eczema en escolares de la ciudad de Cuernavaca, México

Objetivo. La medicion del asma, la rinitis y el eczema ha sido motivo de controversia metodologica por la falta de uniformidad en los diagnosticos operacionales. Con el fin de probar la aplicabilidad de una metodologia estandarizada para comparaciones en tiempo y espacio se determino la prevalencia del asma y de otras enfermedades alergicas en una muestra aleatoria de escolares (n= 6 238) de 6 a 8 anos y de 11 a 14 anos residentes de Cuernavaca, Morelos, Mexico. Material y metodos. Se aplico la metodologia propuesta por el International Study of Asthma and Allergies in Childhood (ISAAC) para determinar la prevalencia y severidad del asma, la rinitis y el eczema. La informacion de prevalencia tanto actual como acumulada para dichos padecimientos se obtuvo a traves de un cuestionario estandarizado contestado por los padres de los ninos. Resultados. La prevalencia acumulada de asma por diagnostico medico y sibilancia fue de 5.8% (5.2-6.4) y 21.8% (20.7-22.9) respectivamente; la prevalencia de sibilancia en los ultimos 12 meses fue de 8.9% en el grupo de 6 a 8 anos contra 6.6% en el de 11 a 14 anos, p< 0.001. La prevalencia de diagnostico medico de rinitis fue de 4.9% (4.3-5.5). Con relacion a los sintomas tipicos de rinitis, en los ultimos 12 meses la prevalencia fue de 9.6% (6 a 8 anos) y de 10.1% (11 a 14 anos). La prevalencia de eczema por diagnostico medico fue de 4.1% (3.6-4.6). La prevalencia de sintomas de eczema en los ultimos 12 meses fue de 10.1% (6 a 8 anos) y de 10.6% (11 a 14 anos). Los sintomas severos de asma fueron significativamente mas prevalentes en el grupo de 6 a 8 anos y en los meses de otono. Conclusiones. La prevalencia de asma tanto por diagnostico medico como por sintomas resulta relativamente baja en relacion con otros estudios realizados con la misma metodologia. Se analizan las bondades del uso de una metodologia estandarizada.

Efecto de la contaminación ambiental sobre las consultas por infecciones respiratorias en niños de la Ciudad de México

Objective. To model the variability of medical visits by children for respiratory reasons as a consequence of the daily changes in environmental pollution observed in the emergency and family medicine departments of a hospital of the Instituto Mexicano del Seguro Social located in the southwest of Mexico City during 1993. Materials and methods. The correlation between the presence of upper and lower respiratory tract infections and exposure to ozone and nitrogen dioxide was studied. To model this association, the authors used multivariate Poisson regression models with linear and non-linear risk, with lag periods between the environmental measurements and the medical visits of one, two and three days, as well as the average of the measurements of three, five and seven days previous to the visit. Results. The model estimates that an increment of 50 ppb in the daily average of ozone would cause an increase of 9.9% in emergency visits due to high respiratory tract infections during the winter, which could rise to 30% if the increment would last five consecutive days in average. Conclusions. Results suggest that exposure of children younger than 15 years of age to ozone and nitrogen dioxide significantly affect the number of medical visits for respiratory causes in this part of Mexico City.

El acoso escolar (bullying) y su asociación con trastornos psiquiátricos en una muestra de escolares en México

OBJETIVO: Estudiar la relacion entre el tipo de psicopatologia y el acoso escolar en una muestra de ninos de las escuelas publicas de la Ciudad de Mexico. MATERIAL Y METODOS: Un total de 1 092 escolares identifico por medio del Test Bull-S a un grupo de agresores,victimas,victima-agresores y neutros. Los padres contestaron la Lista de Sintomas del Nino (Child Behavior Checklist, CBCL) para determinar el rango clinico de psicopatologia. RESULTADOS: El grupo de agresores tuvo asociacion con las escalas de ansiedad, sintomas somaticos, oposicionismo y de conducta. El grupo de victima-agresores presento asociacion con los problemas de atencion,oposicionismo y de conducta.En el grupo de victimas las asociaciones encontradas fueron con los problemas de ansiedad.Estas diferencias fueron significativas frente al grupo control (neutros). CONCLUSION: El acoso escolar se asocia con psicopatologia que requiere de atencion psiquiatrica oportuna.

Personal exposure to PM2.5 air pollution and heart rate variability in subjects with positive or negative head-up tilt test.

Particulate matter air pollution has been related to an increase in cardiopulmonary morbidity and mortality especially in susceptible subjects with a known cardiopulmonary disease. Recent studies suggest that PM(2.5) air pollution was associated with changes in heart rate variability (HRV). The purpose of this study was to identify and compare changes in HRV in positive or negative head-up tilt (HUT) participants. Fifty two subjects, 31 women and 21 men, 20-40 years old, underwent PM(2.5) personal monitoring and Holter-ECG monitoring in supine and orthostatic position, during active standing, in indoor and outdoor environments. All measurements were made between 8 and 11 AM in the same geographical location (southeast of Mexico City). Frequency domain indexes were estimated in absolute (ms(2)) and in normalized units (nu) (low frequencies (LF), high frequencies (HF) and low/high frequency ratio (LF/HF)) in 5 min periods by standard methods. Data were transformed into natural logarithmic scale (ln). Comparisons were made between genders and positive and negative HUT subjects. LF were larger and HF were smaller in negative HUT males. Multivariate analysis with GEE models, adjusted for each index, showed a significant decrease of HRV (LFln -0.194 95% CI, -0.4509, 0.0627, and HFln -0.298 95% CI, -0.5553, -0.0401) associated to an increase in PM(2.5) air pollution in positive and negative HUT subjects which was larger for HFln in outdoor environments. PM(2.5) air pollution was associated with changes in HRV in positive and negative HUT subjects without cardiopulmonary disease.

Dopamine receptor dysregulation in hippocampus of aged rats underlies chronic pulsatile L-Dopa treatment induced cognitive and emotional alterations.

L-Dopa is the major symptomatic therapy for Parkinsons disease, which commonly occurs in elderly patients. However, the effects of chronic use on mood and cognition in old subjects remain elusive. In order to compare the effects of a chronic pulsatile L-Dopa treatment on emotional and cognitive functions in young (3 months) and old (18 months) intact rats, an L-Dopa/carbidopa treatment was administered every 12 h over 4 weeks. Rats were assessed for behavioural despair (repeated forced swimming test, RFST), anhedonia (sucrose preference test, SPT) and spatial learning (Morris water maze, MWM) in the late phase of treatment (T). Neuronal expression of Fos in the hippocampus at the early and late phases of T, as well as after MWM was studied. The density and ratio of dopamine D5r, D3r and D2r receptors were also evaluated in the hippocampus using immunohistochemistry and confocal microscopy. Young rats showed similar patterns during behavioural tests, whereas aged treated rats showed increased immobility counts in RFST, diminished sucrose liquid intake in SPT, and spatial learning impairment during MWM. Fos expression was significantly blunted in the aged treated group after MWM. The density of D5r, D3r and D2r was increased in both aged groups. The treatment reduced the ratio of D5r/D3r and D5r/D2r in both groups. Moreover, aged treated subjects had significant lower values of D5r/D3r and higher values of D5r/D2r when compared with young treated subjects. These results indicate that chronic L-Dopa treatment in itself could trigger emotional and cognitive dysfunctions in elderly subjects through dopamine receptor dysregulation.

Susceptibilidad al consumo de tabaco en estudiantes no fumadores de 10 ciudades mexicanas

OBJETIVO: Identificar la susceptibilidad cognitiva a fumar y los factores asociados en estudiantes de 12 a 15 anos. MATERIAL Y METODOS: Se analizo la medicion basal de una encuesta autoaplicable en 12 293 estudiantes no fumadores de escuelas secundarias, en el ciclo 2005-2006. Susceptible es aquel que contesto que aceptara un cigarrillo de su mejor amigo y cree que el ano proximo fumara. Se obtuvieron modelos de regresion logistica de multinivel. RESULTADOS: La prevalencia de susceptibilidad fue de 30%. Los factores asociados fueron autoestima baja (RM = 1.2, IC95% 1.0-1.5), busqueda de nuevas sensaciones (RM = 1.6, IC95% 1.3-2.0) y actitud favorable a fumar (RM = 2.6, IC95% 2.2-3.2), asi como permisividad social reflejada en reglas del hogar (RM = 2.2, IC95% 1.7-2.8). Solo en mujeres existio interaccion entre permisividad de fumar en el hogar y consumo de tabaco en padres (RM = 2.1, IC95% 1.1-3.8). CONCLUSIONES: La prevencion debe promover la sensibilizacion de profesores y padres de familia como modelos antitabaco e incentivar hogares libres de tabaco.

Benthic bacterial diversity from freshwater tufas of the Iberian Range (Spain)

Aiming to characterize the bacterial diversity of modern tufa systems of the Iberian Range (Spain), we surveyed the 16S rRNA gene sequence diversity from 24 sites within three rivers (Añamaza, Mesa and Piedra). These tufas record substantial calcareous growth under different physicochemical conditions and are part of an important, regional landscape-building system. The bacterial community structure and composition, richness and diversity were quantified from denaturing gradient gel electrophoresis fingerprints. Retrieved DNA sequences could be assigned to 10 bacterial phyla and included a variety of phototrophic and heterotrophic groups. Cyanobacteria, mainly filamentous taxa, constituted 43% of all the retrieved sequences, followed by Firmicutes (11%), Gammaproteobacteria (10%), Alphaproteobacteria (7%), Acidobacteria (6%), Bacteroidetes (5%), Betaproteobacteria (4%), Planctomycetes (4%), Actinobacteria (3%) and Deltaproteobacteria (2%). Diatom and Xanthophyceae chloroplast sequences were also detected. Physicochemical variables measured at each site were modelled with multivariate statistics. Principal component analyses yielded the highest variance for salinity-related variables (conductivity; Na(+) , Cl(-) and SO4(2-) concentrations), which correlated negatively and significantly with diversity indices. However, the highest variance explained by individual principal components was relatively low (< 34%). Overall, we show that these young fluvial tufas are inhabited by a large variety of bacteria in diverse and widespread communities.

The Application of a New Dependency Measure to Principal Component Analysis

Abstract In this article we study the relationship between principal component analysis and a multivariate dependency measure. It is shown, via simulated examples and real data, that the information provided by principal components is compatible with that obtained via the dependency measure δ. Furthermore, we show that in some instances in which principal component analysis fails to give reasonable results due to nonlinearity among the random variables, the dependency statistic δ still provides good results. Finally, we give some ideas about using the statistic δ in order to reduce the dimensionality of a given data set.

Assessment of depressive symptoms in severe smokers with minimal-mild depressive symptomatology receiving pre-smoking abstinence for integrated treatment: a randomized clinical trial

Introduction. Smoking and depression have a long-history documented of comorbidity. Objective. The objective of this study was to develop and test a treatment that could simultaneously achieve smoking abstinence and decrease depressive symptoms in a group of heavy smokers with minimal/mild depressive symptomatology. Method. Sixty smokers were randomly assigned to three different treatment settings. Treatment included a pre-abstinence phase, a psychological treatment phase, a pharmacotherapy phase and a follow-up stage. Smokers began the psychological treatment and the pharmacotherapy two weeks before the day they chosen to quit smoking, and monitoring was conducted over a year. Abstinence was confirmed by assessing the levels of urinary cotinine. Results. Using a linear mixed model with individual random effect, baseline data was compared with subsequent assessments; 46% of the patients achieved abstinence. For men, the three treatment settings significantly reduced depressive symptoms and helped smokers to achieve abstinence. For women, only the nicotine patch showed to be effective in the reducing depressive symptoms. Discussion and conclusion. Integral pre-abstinence treatment is effective in aiding smokers to achieve smoking abstinence and improve depressive symptoms.

Reduction in Measurement Error: Barraza-Villarreal et al. Respond.

We thank Barnett for his comments on our article (Barraza-Villarreal et al. 2008), in which we reported associations between ambient air pollution and adverse lung function outcomes in a cohort of schoolchildren in Mexico City, Mexico. In the last several years, the adverse effects of air pollution on lung function, such as decrement in forced expiratory volume in 1 sec (FEV1) has been clearly demonstrated (Gauderman et al. 2007; Romieu et al. 1997). Before our study, there were reports of associations between cumulative particulate matter [PM < 10 μm (PM10) and < 2.5 μm (PM2.5 ) in aerodynamic diameter] and gaseous (ozone, sulfur dioxide, and nitrogen dioxide) air pollutant exposure and decrease in lung function in other studies (Downs et al. 2007; Romieu et al. 2006). Replication of these findings in different populations under different conditions of exposure is an important aspect of epidemiologic research, with consistency of results strengthening the weight of evidence for a true association between exposure and outcome. However, air pollution exposure assessment is always a critical factor in environmental epidemiology. Like other studies of air pollution and lung health, our study (Barraza-Villarreal et al. 2008) relied on ecologic rather than personal indicators of exposure. Exposure misclassification due to the use of fixed-site ambient monitors rather than personal dosimeters is likely to underestimate rather than overestimate the effect of air pollution on lung function. In his letter Barnett mentions that “the apparent stronger association between reduced FEV1 and cumulative exposure over 1–5 days may be due in part to a reduction in measurement error of particulate matter < 2.5 μm (PM2.5) and not a true cumulative effect.” He attempted to verify this assertion by carrying out a simulation study; however, we see several problems with it. First, in his simulations, Barnett assumed a normal distribution (Figure 1). Several distributions have been reported as adequate for PM2.5, among them log-logistic, log-normal, and gamma. Using the data from our study (Barraza-Villarreal et al. 2008), we carried out an exercise similar to Barnett’s, but we fitted different distributions (data not shown). The one that best fit our data was the gamma distribution. Second, when considering cumulative exposure, it is important to take into account the correlation between the observations on consecutive days; it is not enough to simulate from a distribution and then add the exposure. The models presented by Barnett did not take into account this correlation. Third, we reproduced the simulation of FEV1 as presented by Barnett (data not shown) and observed that it could produce negative value for FEV1 because it does not take into account the correlation of observations within children, although a sample size for each child was simulated and an artificial mixed model was fitted. Figure 1 Same day (A,B) and 2-day cumulative (C,D) PM2.5 distributions. (A,C) original data. (B,D) Simulated data. In conclusion, because Barnett’s simulation of PM2.5 was based on a normal distribution, it does not reproduce the original structure of our data (Figure 1) (Barraza-Villarreal et al. 2008); therefore, the conclusions obtained are not applicable.