Conductance heterogeneities induced by multistability in the dynamics of coupled cardiac gap junctions.

In this paper, we study the propagation of the cardiac action potential in a one-dimensional fiber, where cells are electrically coupled through gap junctions (GJs). We consider gap junctional gate dynamics that depend on the intercellular potential. We find that different GJs in the tissue can end up in two different states: a low conducting state and a high conducting state. We first present evidence of the dynamical multistability that occurs by setting specific parameters of the GJ dynamics. Subsequently, we explain how the multistability is a direct consequence of the GJ stability problem by reducing the dynamical system's dimensions. The conductance dispersion usually occurs on a large time scale, i.e., thousands of heartbeats. The full cardiac model simulations are computationally demanding, and we derive a simplified model that allows for a reduction in the computational cost of four orders of magnitude. This simplified model reproduces nearly quantitatively the results provided by the original full model. We explain the discrepancies between the two models due to the simplified model's lack of spatial correlations. This simplified model provides a valuable tool to explore cardiac dynamics over very long time scales. That is highly relevant in studying diseases that develop on a large time scale compared to the basic heartbeat. As in the brain, plasticity and tissue remodeling are crucial parameters in determining the action potential wave propagation's stability.

IgE responses to Ascaris and mite tropomyosins are risk factors for asthma.

BACKGROUND: The relationship between helminthiases and allergy is a matter of considerable interest and research. In the tropics, house dust mite exposure, a known risk factor for asthma, is frequently concurrent with helminth infections. It remains to be defined whether infection with the common roundworm Ascaris or its bystander immunological effects influence the prevalence and pathogenesis of asthma independently of mite sensitization. OBJECTIVE: To investigate the relationship between the IgE responses to Ascaris and its purified allergens and the risk of asthma in a tropical country. METHODS: A nested case-control study was performed in 356 subjects who reported current and past asthma symptoms (asthmatics) and 435 controls that had never experienced such symptoms. They were tested for serum levels of total IgE and specific IgE to Ascaris extract, Asc s 1 (ABA-1), Asc l 3 (tropomyosin) and GST (glutathione transferase). In addition, specific IgE to Dermatophagoides pteronyssinus, Blomia tropicalis and their tropomyosins Der p 10 and Blo t 10 was measured. Sensitization was defined as a positive specific IgE result to any extract or recombinant allergen. RESULTS: Sensitization to Ascaris and D. pteronyssinus was independently associated with asthma after adjustment for age, gender, socio-economic stratum, city and other IgE levels (adjusted ORs: 2.17; 95% CI 1.37-3.42 and 2.46; 95% CI 1.54-3.92), respectively. There was also a significant association with sensitization to the highly allergenic and cross-reactive tropomyosins Asc l 3, Blo t 10 and Der p10 (aORs: 1.76; 95% CI 1.21-2.57, 1.64; 95% CI 1.14-2.35 and 1.51; 95% CI 1.02-2.24), respectively. CONCLUSION AND CLINICAL RELEVANCE: IgE responses to Ascaris are associated with asthma symptoms in a population living in the tropics. Sensitization to the cross-reactive Ascaris and mite tropomyosins partially underlies this finding. These results have potential relevance in asthma diagnosis and management.

Allergic rhinitis and associated factors in schoolchildren from Bogota, Colombia.

BACKGROUND: Allergic rhinitis is one of the most frequent chronic diseases among children. The objective of the study was to assess the prevalence of and the factors associated with self-reported allergic rhinitis symptoms in schoolchildren from Bogota, Colombia. METHODOLOGY/PRINCIPAL: We followed the International Study of Asthma and Allergies in Childhood (ISAAC) methodology. Our sample included 3,256 children aged 6 - 7 and 3,830 adolescents aged 13 - 14 years. RESULTS: The prevalence of self-reported allergic rhinitis symptoms was 30.8% among children and 36.6% among adolescents. Factors associated with self-reported allergic rhinitis among children included current asthma and atopic dermatitis symptoms; use of acetaminophen in the first year of life and in the last 12 months; antibiotic use in the first year of life; high- school and university maternal education; smokers at home; and caesarean delivery. Among adolescents, associated factors included current asthma and atopic dermatitis symptoms; current acetaminophen use once per month; frequent fast-food consumption; cat exposure at home; and smoking. CONCLUSION: Further exploration of factors associated with allergic rhinitis symptoms is needed.

Analysis of tinnitus severity and associated risk factors in patients with chronic otitis media: data from the multinational collaborative Chronic Otitis Media Questionnaire-12 study.

BACKGROUND: Subjective tinnitus is a common symptom, and there is often an underlying otological cause. This study investigated the degree of tinnitus-related annoyance in patients with chronic otitis media and analysed whether associations with tinnitus severity exist. METHOD: The multinational collaborative Chronic Otitis Media Questionnaire-12 study collected prospective data on 478 adult patients suffering from chronic otitis media across 9 otology referral centres in 8 countries. Based on this dataset, we investigated tinnitus severity using participant responses to item 7 of a native version of the Chronic Otitis Media Questionnaire-12. RESULTS: With respect to tinnitus severity, 23.8 per cent, 17.4 per cent, 15.5 per cent, and 43.4 per cent of participants reported no, minor, moderate, and major inconvenience or greater, respectively. The absence of ear discharge, absence of cholesteatoma, and poorer disease-specific health-related quality-of-life were associated with increased tinnitus severity in patients with chronic otitis media, whereas age, hearing disability and geographical region showed no association. CONCLUSION: This analysis provided novel insight into potential risk factors for tinnitus in patients with chronic otitis media.

Opthalmological sequelae due to paintball injuries: Case studies. / Secuelas oftalmológicas por traumatismo con paintball: estudio de casos.

OBJECTIVE: Describe the ophthalmological sequelae of patients diagnosed with blunt eye injury by paintball. MATERIAL AND METHODS: There were a total 14 cases with a diagnosis of blunt trauma by paintball were treated at the ophthalmology emergency department of the Barraquer Clinic in Bogotá, Colombia. All patients underwent a complete ophthalmological examination with their respective controls according to their outcome. RESULTS: The frequency of eye trauma by paintball was 3.01%. Fourteen eyes were evaluated, age range from 9 to 49 years. Cases were unilateral, 1 woman and 13 men, initial visual acuity less than 20/30 in 12 eyes. Only 5 eyes progressed satisfactorily, and 3 were surgically intervened. The cases that did not show any improvement in visual acuity were related to posterior pole problems, with the most frequent being macular alterations, choroidal rupture, choroidal detachment, retinal tear, and retinal folds. In 3eyes, clinical improvement of visual acuity was evidenced secondary to haemorrhagic processes that resolved with medical treatment. One of them underwent surgical treatment of the lens with an intraocular lens implant. In 2eyes, the visual recovery was very satisfactory and 100% in another. CONCLUSION: Paintball has increased as a sport and recreational activity, where paint projectiles are fired with compressed air weapons. It carries risks of suffering various trauma that can lead to catastrophic episodes, in terms of visual health, and repercussions on the quality of life of those affected.

[Intracoronary ultrasound: A necessary tool for stent implantation? Arguments in against]. / Ultrasonidos intracoronarios: una técnica necesaria en la implantación de stents? Argumentos en contra.

Intracoronary ultrasound has shown the little reliability of angiography to predict the interaction of stents with the arterial wall. In spite of implanting the stents with high pressures and a good angiographic result, a great proportion are still incompletely expanded. The use of intracoronary ultrasound as a guide for stent implant allows us to optimize the degree of expansion and apposition of the stent to the arterial wall, achieving greater intraluminal dimensions than with angiography. Nevertheless, this strategy is not necessarily translated in a clear clinical benefit. The rate of acute and subacute complications of stents implanted under angiographic control with high pressures and treatment with ticlopidine and aspirin is less than 1% and identical to the studies that use intracoronary ultrasound to optimize stent deployment. At the present time, it has not been documented either that the optimization of stent deployment with intracoronary ultrasound significantly reduces the rate of restenosis, the incidence of target vessel revascularization or the rate of major adverse cardiac events in mid-term follow-up. In addition, the use of intracoronary ultrasound to optimize stent deployment adds a small risk to the procedure, extends the time of occupation of the cardiac catheterization laboratory and prohibitively increases the costs of coronary stenting them being already high ones. Thus, the universal use of coronary intracoronary ultrasound to optimize stent deployment seems not to be, at present, a useful strategy.

Surgical treatment and rehabilitation of prelingually and perilingually deafened children and adults with the nucleus multichannel cochlear implant.

We began our program in September 1992, using the Nucleus 22 Channel Cochlear Implant. To date, we have operated on four patients, one child with congenital hearing loss, two prelinguistically deaf adults and one perilingually deaf adult. Our results have shown a significant increase in auditory and speech reception and perception skills in the child. The perilingually deaf adult is able to understand speech in open set speech discrimination testing and, although we do not expect open set speech discrimination in the prelinguistically deaf adults, to date their results have been satisfactory. The two prelingually deaf adults are in an audiological rehabilitation program. Their response in prosodic aspects of speech and lipreading ability with sound have improved significantly. The only surgical complication was an infection of the flap in the child, but it was treated satisfactorily with i.v. penicillin.

Modeling of spatiotemporal patterns in bacterial colonies.

A diffusion-reaction model for the growth of bacterial colonies is presented. The often observed cooperative behavior developed by bacteria which increases their motility in adverse growth conditions is here introduced as a nonlinear diffusion term. The presence of this mechanism depends on a response which can present hysteresis. By changing only the concentrations of agar and initial nutrient, numerical integration of the proposed model reproduces the different patterns shown by Bacillus subtilis OG-01.

Rheological behavior of Phanerochaete chrysosporium broth during lignin degradation.

Rheological behavior of a lignin-degrading culture of Phanerochaete chrysosporium CDBB-H-298 was determined. Rheological characteristics revealed a Newtonian behavior in the culture medium without fungi, and a non-Newtonian dilatant behavior with fungi. In addition, the rheological behavior of the lignin-containing culture medium was complex, and changed from dilatant to pseudoplastic. During fungal growth without lignin in Kirk media rheological behavior exhibited a parabolic profile, and thixotropy showed a tendency to increase. Results indicated a small increase in the apparent viscosity in the presence of lignin; however, this may not affect the oxygen and mass transfer coefficients. The present findings can be applied to bioreactor desing for waste water treatment.

El implante coclear en la sordera de larga evolución / Cochlear implant in long evolution deafness

En Colombia un número significativo de pacientes con sorderas neurosensoriales de larga evolución (congénitas o adquiridas en el primer año de vida ) son potenciales candidatos para el implante coclear, como una alternativa de rehabilitación en su vida cotidiana. Se ha reportado ampliamente en la literatura que los beneficios del implante coclear son restringidos en éste grupo de individuos y que los ciriterios de selección deben ser muy estrictos, especialmente en países con recursos limitados. Sin duda alguna el implante coclear mejora la comunicación y las habilidades auditivas en las sorderas prelinguales en diverso grado. Aún algunos pacientes alcanzan diferencias estadísticamente significativas en las pruebas de contexto abierto. En el presente artículo presentamos los resultados de la investigación donde se analizan los datos en los pacientes prelinguales con sorderas de larga evolución y las variables que afectan las diferencias observadas. De un total de 117 pacientes seleccionamos 31 pacientes prelinguales con una deprivación auditiva mayor de 12 años. Luego de analizar resultados se observa una mejoría estadísticamente significativa en las pruebas de prosodia y contexto cerrado. Las mayores diferencias se observan en los resultados de contexto abierto y luego de una análisis estadístico univariable y multivariable se concluye que los factores más importantes que influyen en mejores resultados son el uso consistente de audífonos, el tipo de rehabilitación, la rehabilitación continua luego del implante y una adecuada motivación a la comunicación oral. Estos aspectos son fundamentales para decidir los beneficios o limitaciones del implante coclear en éste grupo de pacientes

Estudio multicéntrico abierto no comparativo sobre la eficacia y la seguridad del acetónido de triamcinolona -inhalador nasal- una vez al día por tres meses en los síntomas de rinitis alérgica perenne / Non operative open label multicenter study on the efficacy and security of triamcinolone acetonide -nasal inhalator- once daily for three months in the treatment of the symptoms of permanent allergic rhinitis

Objetivo: evaluar la respuesta clínica (evolución de los síntomas de rinitis y manifestaciones alérgicas) en un grupo de pacientes con diagnóstico de rinitis alérgica perenne, luego de la administración de acetónido de triamcinolona -inhalador nasal- 110 a 220 mcg/1 vez al día (según la edad y severidad de los síntomas) y describir la tolerabilidad de la medicación administrada durante 3 meses. Diseño: estudio clínico observacional, descriptivo (serie de casos)., fase IV, no comparativo, abierto. Pacientes centros: fueron incluidos en el estudio 61 pacientes evaluados en 14 centros, con diagnóstico de rinitis alérgica perenne, mayores de 4 años, sin contraindicaciones para administración de acetónido de triamcinolona. Variables de seguridad y eficacia: frecuencia de eventos adversos. Evolución de una escala de severidad de la sintomatología de rinitis en 4 dominios: congestión nasal, estornudos, prurito y secreción nasal. Evaluación global subjetiva de mejoría por parte del médico tratante y del paciente. Resultados: se reclutaron 61 pacientes, 26 hombres (42,6 por ciento) y 35 mujeres (57,4 por ciento), con edades entre 4 y 48 años (promedio: 23 años). El seguimiento planeado a 3 meses fue logrado en 52 sujetos. Se administró una dosis diaria de acetónido de triamcinolona -inhalador nasal- por un período de 12 semanas. Los pacientes fueron evaluados antes de iniciar el tratamiento y a las semanas 6 y 12. Se produjo una reducción significativa en el puntaje de severidad de la rinitis de un valor mediano de 10 antes de tratamiento a 0 a las 12 semanas (p<0,001). No se presentaron efectos adversos severos y solo un efecto leve (costras nasales) fue relacionado con la administración de acetónido de triamcinolona -inhalador nasal- , no obstante no se requirió descontinuar el medicamento. Conclusiones: el tratamiento de los síntomas de la rinitis alérgica perenne con acetónido de triamcinolona -inhalador nasal- mostró una reducción clínica y estadísticamente significativa de la sintomatología en la mayoría de los pacientes tratados y fue excelentemente tolerado