High Incidence of Sleep-Related Breathing Disorders in Children with Down Syndrome Referred to a High-Altitude Sleep Laboratory.

Aims: The aim of the study was to assess the incidence of sleep-related breathing disorders (SRBD) in children with Down Syndrome (DS) living at high altitude. Methods: A retrospective descriptive study was conducted on 53 children with DS who underwent polysomnography (PSG) at San Ignacio University Hospital (2640 m/8660 ft above sea level) from 2009 to 2016. Data were extracted from official PSG reports and analyzed using measures of central tendency and dispersion, frequency calculation, ranges, and confidence intervals. Associations were examined using t-test, chi-square test, and analysis of variance test. Results: Obstructive sleep apnea (OSA) was present in 90.5% of children. Central sleep apnea was evident in 11.3%. Periodic breathing was seen in 15.1% of patients. Snoring was able to predict OSA with a sensitivity of 61.7%, a specificity of 100%, and negative predictive value of 25%. Conclusion: Children with DS who live at high altitude have a high incidence of SRBD. Our findings show a higher incidence of SRBD than previously reported in the population with DS. Furthermore, snoring was not sensitive enough to predict OSA. This high risk of SRBD may increase the risk of other comorbid conditions seen in the population with DS. Our results support the need for routine PSG screening independent of symptoms such as snoring status.

Human platelet interaction with E. coli O111 promotes tissue-factor-dependent procoagulant activity, involving Toll like receptor 4.

Platelets have a major role in clotting activation and contribute to the innate immune response during systemic infections. Human platelets contain tissue factor (TF) and express functional Toll-like receptor 4 (TLR4). However, the role of TLR4 in triggering the procoagulant properties of platelets, upon challenge with bacteria, is yet unknown. Our hypothesis is that E. coli O111-TLR4 interaction activates platelets and elicits their procoagulant activity. We demonstrated that the strain, but not ultrapure LPS, increased surface P-selectin expression, platelet dependent TF procoagulant activity (TF-PCA) and prompted a faster thrombin generation (TG). Blockade of TLR4 resulted in decreased platelet activation, TF-PCA and TG, revealing the participation of this immune receptor on the procoagulant response of platelets. Our results provide a novel mechanism by which individuals with bacterial infections would have an increased incidence of blood clots. Furthermore, the identification of platelet TF and TLR4 as regulators of the effect of E. coli O111 might represent a novel therapeutic target to reduce the devastating consequences of the hemostatic disorder during sepsis.

Platelet tissue factor activity and membrane cholesterol are increased in hypercholesterolemia and normalized by rosuvastatin, but not by atorvastatin.

BACKGROUND AND AIMS: High plasma LDL-cholesterol (LDL-C) and platelet responses have major pathogenic roles in atherothrombosis. Thus, statins and anti-platelet drugs constitute mainstays in cardiovascular prevention/treatment. However, the role of platelet tissue factor-dependent procoagulant activity (TF-PCA) has remained unexplored in hypercholesterolemia. We aimed to study platelet TF-PCA and its relationship with membrane cholesterol in vitro and in 45 hypercholesterolemic patients (HC-patients) (LDL-C >3.37 mmol/L, 130 mg/dL) and 37 control subjects (LDL-C <3.37 mmol/L). The effect of 1-month administration of 80 mg/day atorvastatin (n = 21) and 20 mg/day rosuvastatin (n = 24) was compared. METHODS: Platelet TF-PCA was induced by GPIbα activation with VWF-ristocetin. RESULTS: Cholesterol-enriched platelets in vitro had augmented aggregation/secretion and platelet FXa generation (1.65-fold increase, p = 0.01). HC-patients had 1.5-, 2.3- and 2.5-fold increases in platelet cholesterol, TF protein and activity, respectively; their platelets had neither hyper-aggregation nor endogenous thrombin generation (ETP). Rosuvastatin, but not atorvastatin, normalized platelet cholesterol, TF protein and FXa generation. It also increased slightly the plasma HDL-C levels, which correlated negatively with TF-PCA. CONCLUSIONS: Platelets from HC-patients were not hyper-responsive to low concentrations of classical agonists and had normal PRP-ETP, before and after statin administration. However, washed platelets from HC-patients had increased membrane cholesterol, TF protein and TF-PCA. The platelet TF-dependent PCA was specifically expressed after VWF-induced GPIbα activation. Rosuvastatin, but not atorvastatin treatment, normalized the membrane cholesterol, TF protein and TF-PCA in HC-patients, possibly unveiling a new pleiotropic effect of rosuvastatin. Modulation of platelet TF-PCA may become a novel target to prevent/treat atherothrombosis without increasing bleeding risks.

Association of Cardiovascular Disease and Sleep Apnea at Different Altitudes.

Otero, Liliana, Patricia Hidalgo, Rafael González, and Carlos A. Morillo. Association of cardiovascular disease and sleep apnea at different altitudes. High Alt Med Biol. 17:336-341, 2016.-We evaluated the prevalence of sleep apnea (SA) in patients with cardiovascular disease (CVD) at different altitudes. A total of 398 subjects with coronary artery disease (CAD), 144 subjects with atrial fibrillation (AF), and 292 controls (without CVD) were recruited in three cities at sea level, moderate altitude, and high altitude. All participants underwent polysomnography. Multinomial logistic regression, X2, and Hosmer and Lemeshow tests were used to determine interactions among CVD, SA, and altitude. Men and women with CVD at high altitude had a higher risk for SA than men and women living at lower altitudes. The highest risk of SA was observed in men with AF and men with CAD living at high altitude. Obstructive SA (OSA) prevalence was significantly increased in CVD subjects living at high altitude (OR: 5.52; p < 0.0001). Central SA (CSA) was more frequent in subjects with CVD than control group (OR: 2.44; p < 0.021). OSA was the most frequent type of SA in subjects with CVD and overweight subjects, and in control individuals with obesity or being overweight. Significant differences in the prevalence of SA associated with altitude and gender were noted in subjects with CAD and AF.

Análisis de costo-efectividad de pramipexol comparado con levodopa y cabergolina para pacientes con síndrome de piernas inquietas en Colombia / Análise de custo-eficácia do pramipexol e cabergolina comparação com levodopa para pacientes com síndrome das pernas inquietas na Colômbia

Problema de investigación: Describir los costos y la efectividad del pramipexol comparado con levodopa y cabergolina para el tratamiento de pacientes con síndrome de piernas inquietas.Tipo de evaluación económica\r\nAnálisis de costo-utilidad. Población objetivo: Población adulta con diagnóstico de síndrome de piernas inquietas. Intervención y comparadores: Intervención: Pramipexol, Comparadores: Levodopa y cabergolina. Horizonte temporal: 16 semanas. Perspectiva Sistema: General de Seguridad Social en Salud (SGSSS). Tasa de descuento: No aplica. Estructura del modelo: Modelo de Markov. Fuentes de datos de efectividad y \r\nseguridad: Reporte de efectividad y seguridad elaborado en diciembre de 2014 en el IETS, Ensayos clínicos aleatorizados. Desenlaces y valoración: Años de vida ajustados por calidad (AVAC). Costos incluidos: Costos de medicamentos, Costos de procedimientos. Fuentes de datos de costos:SISMED, Manual tarifario ISS 2001. Resultados del caso base: En el escenario del caso base, pramipexol es una estrategia costo-efectiva con respecto a levodopa. El costo por AVAC ganado con pramipexol es de $7.480 comparado con levodopa. Análisis de sensibilidad: El análisis de sensibilidad determinístico y el diagrama de tornado mostraron que la variable con mayor impacto sobre las estimaciones de costo-efectividad es el precio de levodopa. No se realizó análisis de sensibilidad probabilístico. Conclusiones y discusión: Pramipexol ofrece una mejor relación entre costos y efectividad respecto a levodopa y cabergolina. De acuerdo con el criterio de los expertos clínicos la cabergolina no hace parte de la práctica clínica habitual para este trastorno y la \r\nlevodopa tiene un uso que requiere de supervisión por el efecto que agudiza las manifestaciones clínicas. La principal limitación de este estudio está relacionada con la poca información proveniente de estudios de investigación clínica y evaluaciones económicas.(AU)

Análisis de impacto presupuestal de pramipexol comparado con levodopa como terapia de primera línea para pacientes con síndrome de piernas inquietas en Colombia / Budget impact analysis of pramipexole compared to levodopa as first-line therapy for patients with restless legs syndrome in Colombia

Tecnologías evaluadas: Nuevas: pramipexol y cabergolina; Actuales: levodopa (en combinación con carbidopa). Población: Pacientes mayores de 18 años con síndrome de piernas inquietas. Perspectiva: La perspectiva del presente AIP corresponde al tercero pagador, que en este caso es el Sistema General de Seguridad Social en Salud (SGSSS) en Colombia. Horizonte temporal: El horizonte temporal de este AIP en el caso base corresponde a un año. Adicionalmente se reportan las estimaciones del impacto presupuestal para los años 2 y 3, bajo el supuesto de la inclusión en el POS en el año 1. Costos incluidos: Costo por mg de los medicamentos. Fuente de costos: Sistema de información de Precios de Medicamentos y Dispositivos Médicos - SISMED. Escenarios: En la construcción de escenarios se consideró una participación de\r\nmercado más alta para pramipexol en comparación con levodopa. Lo anterior a partir de las recomendaciones resultado de la consulta con expertos y la participación de mercado de los medicamentos en el SISMED. \r\nResultados: Para la inclusión en el POS de pramipexol y cabergolina como terapia de primera línea para pacientes con síndrome de piernas inquietas en Colombia, se requeriría una inversión de $21.708.230.419 en el año 1 y de $53.499.840.477 en el año 3. En el caso que los medicamentos del escenario nuevo sean incluidos con un precio común basado en las metodologías de grupos terapéuticos del Ministerio de Salud y protección Social, el impacto presupuestal sería el mismo con una inversión de $21.708.230.419 en el año 1 y $53.499.840.477, en el año 3.(AU)

Impacto en la calidad de vida por la asociación entre trastornos de sueño y síndrome de intestino irritable / Impact on the Quality of Life of the Association between Sleep Disorders and Irritable Bowel Syndrome

Objetivos: determinar si la presencia de alteraciones del sueño se asocia con el deterioro en la calidad de vida, medida a través del cuestionario SF-36, en pacientes con síndrome de intestino irritable (SII). Métodos: se diseñó un estudio de corte transversal en el que se incluyeron individuos con SII seleccionados con los criterios de Roma III, a los que se les aplicó la escala de Epworth, el cuestionario de Pittsburgh y los criterios para síndrome de piernas inquietas (SPI); de manera simultánea, se les realizó la evaluación de calidad de vida usando la escala SF-36. Resultados: se incluyeron 80 pacientes con SII, la mayoría mujeres; el 81% presentó algún tipo de trastorno del sueño determinado por la alteración en 1 o más escalas. Al estratificar los pacientes con y sin trastornos del sueño, se observó que el subgrupo con trastorno del sueño se asoció con mayores alteraciones en la calidad de vida, con OR 4,8125, IC 95%: 1,17-19,02, p < 0,0076, diferencia estadísticamente significativa. Conclusiones: en este estudio se encontró que hasta un 81% de los pacientes con SII presentan trastornos de sueño, y que las alteraciones del sueño en pacientes con SII se asocian con un mayor compromiso de la calidad de vida según la escala SF-36.

Objectives: The objectives of this study were to determine if sleep disorders in patients with irritable bowel syndrome (IBS) were associated with impaired quality of life as measured by the SF36 questionnaire. Methods: This is cross-sectional study in which individuals with IBS according to the Rome III criteria were evaluated for sleep disorders with the Epworth Sleepiness Scale questionnaire and the Pittsburgh Sleep Quality Index (PSQI) questionnaire. They were also evaluated for restless legs syndrome (RLS) and, simultaneously, the Short Form (36) Health Survey was used to evaluate participants’ quality of life. Results: Eighty patients with IBS, mostly women, were included in this study. 81% had some type of specific sleep disorder as measured by at least one of the questionnaires. Patients were groups into those who had sleep disorders, and those who did not. The group which had sleep disorders had statistically significantly more alterations in quality of life (OR 4.8125, 95% CI: 1.17 to 19.02, p <0.0076). Conclusions: This study found that up to 81% of IBS patients have sleep disorders and that sleep disturbances in patients with IBS are associated with decreased quality of life according to the SF36 scale.

[Phenotypic and genotypic diagnosis of bone and miliary tuberculosis in an HIV+ patient in Bogotá, Colombia]. / Diagnóstico genotípico y fenotípico de tuberculosis ósea y miliar en un paciente positivo para HIV en Bogotá, Colombia.

Tuberculosis is the single most frequent cause of death by an infectious agent worldwide. Diagnosis of extra-pulmonary tuberculosis is not always possible through conventional methods, due to the long time required for cultures and the paucibacillary nature of samples; hence the need of rapid molecular methods. HIV infection increases the risk of tuberculosis, and HIV/tuberculosis coinfection is associated with higher mortality. We describe the case of a 56-year old mestizo male patient suspected of having tuberculosis who consulted the San Ignacio Hospital in Bogotá with a two-month history of a painful ulcerated lesion over the distal third area of the right forearm and in whom HIV coinfection was confirmed. Bone and pulmonary histological examination evidenced multiple granulomas, giant cells and fibrosis. Cultures and IS6110-PCR from lung and bone tissues were positive for Mycobacterium tuberculosis complex. Mycobacterium tuberculosis isolates were sensitive to first line drugs.

Platelets enhance tissue factor protein and metastasis initiating cell markers, and act as chemoattractants increasing the migration of ovarian cancer cells.

BACKGROUND: An increase in circulating platelets, or thrombocytosis, is recognized as an independent risk factor of bad prognosis and metastasis in patients with ovarian cancer; however the complex role of platelets in tumor progression has not been fully elucidated. Platelet activation has been associated with an epithelial to mesenchymal transition (EMT), while Tissue Factor (TF) protein expression by cancer cells has been shown to correlate with hypercoagulable state and metastasis. The aim of this work was to determine the effect of platelet-cancer cell interaction on TF and "Metastasis Initiating Cell (MIC)" marker levels and migration in ovarian cancer cell lines and cancer cells isolated from the ascetic fluid of ovarian cancer patients. METHODS: With informed patient consent, ascitic fluid isolated ovarian cancer cells, cell lines and ovarian cancer spheres were co-cultivated with human platelets. TF, EMT and stem cell marker levels were determined by Western blotting, flow cytometry and RT-PCR. Cancer cell migration was determined by Boyden chambers and the scratch assay. RESULTS: The co-culture of patient-derived ovarian cancer cells with platelets causes: 1) a phenotypic change in cancer cells, 2) chemoattraction and cancer cell migration, 3) induced MIC markers (EMT/stemness), 3) increased sphere formation and 4) increased TF protein levels and activity. CONCLUSIONS: We present the first evidence that platelets act as chemoattractants to cancer cells. Furthermore, platelets promote the formation of ovarian cancer spheres that express MIC markers and the metastatic protein TF. Our results suggest that platelet-cancer cell interaction plays a role in the formation of metastatic foci.

Diagnóstico genotípico y fenotípico de tuberculosis ósea y miliar en un paciente positivo para HIV en Bogotá, Colombia / Phenotypic and genotypic diagnosis of bone and miliary tuberculosis in an HIV+ patient in Bogotá, Colombia

La tuberculosis se considera la causa más frecuente de muerte producida por un solo agente infeccioso. El diagnóstico de la tuberculosis extrapulmonar no siempre es posible mediante los métodos convencionales debido al lento crecimiento del bacilo y a la naturaleza paucibacilar de las muestras, por lo que es necesario recurrir a las técnicas moleculares. El riesgo de tuberculosis, así como la mortalidad, aumenta en los pacientes con infección por HIV, en quienes el compromiso extrapulmonar es más frecuente. Se describe el caso de un hombre mestizo de 56 años de edad con sospecha de padecer tuberculosis, que asistió a consulta en el Hospital San Ignacio de Bogotá y relató haber tenido dolor en una lesión ulcerada localizada en el tercio distal del antebrazo derecho durante los dos meses anteriores y en quien se confirmó la infección por HIV. El examen histológico de los tejidos óseo y pulmonar demostró la presencia de granulomas múltiples, células gigantes y fibrosis. Tanto los cultivos como la reacción en cadena de la polimerasa en la secuencia de inserción 6110 ( insertion sequence , IS6110) fueron positivos. Los aislamientos de Mycobacterium tuberculosis recuperados fueron sensibles a los medicamentos antituberculosos de primera línea.

Tuberculosis is the single most frequent cause of death by an infectious agent worldwide. Diagnosis of extra-pulmonary tuberculosis is not always possible through conventional methods, due to the long time required for cultures and the paucibacillary nature of samples; hence the need of rapid molecular methods. HIV infection increases the risk of tuberculosis, and HIV/tuberculosis coinfection is associated with higher mortality. We describe the case of a 56-year old mestizo male patient suspected of having tuberculosis who consulted the San Ignacio Hospital in Bogotá with a two-month history of a painful ulcerated lesion over the distal third area of the right forearm and in whom HIV coinfection was confirmed. Bone and pulmonary histological examination evidenced multiple granulomas, giant cells and fibrosis. Cultures and IS6110-PCR from lung and bone tissues were positive for Mycobacterium tuberculosis complex. Mycobacterium tuberculosis isolates were sensitive to first line drugs.

Síndrome de apnea/hipopnea obstructiva del sueño y su asociación con las enfermedades cardiovasculares / Obstructive Sleep Apnea Hypopnea Syndrome and its association with cardiovascular disease

Introducción:El síndrome de apnea/hipopnea obstructiva del sueño, es una entidad que ha cobrado importancia en los últimos años, con una prevalencia estimada en adultos de edad media cercana al 4 y al 2% en hombres y mujeres, respectivamente, y que por su frecuencia constituye un problema de salud pública. Objetivo:Exponer, tras un análisis exhaustivo de la literatura disponible, la asociación entre el síndrome de apnea/hipopnea obstructiva del sueño y las enfermedades cardiovasculares. Método: Se hizo una revisión narrativa a partir de la literatura encontrada en las bases de datos más reconocidas. Se incluyeron 59 estudios publicados en los últimos treinta años y se excluyeron reportes y series de casos. Conclusiones: El síndrome de apnea/hipopnea obstructiva del sueño se reconoce hoy en día como un problema de salud pública mundial. En Latinoamérica, más específicamente en Colombia, se requieren estudios prospectivos de cohorte que sirvan de pauta para la población del continente e indiquen posibles diferencias respecto a la comunidad internacional en cuanto a su tratamiento y diagnóstico oportunos, así como acerca del impacto de estos en lo concerniente a los desenlaces cardiovasculares de los pacientes.

Introduction: The Obstructive Sleep Apnea Hypopnea Syndrome has gained importance has gained importance in recent years, with an estimated prevalence in population of middle-aged adults around 4 and 2% in men and women respectively, and that given its frequency constitutes a public health problem. Objective: To show, after a thorough analysis of the available literature, the association between the Obstructive Sleep Apnea Hypopnea Syndrome and cardiovascular diseases. Method: A narrative review was made from the literature found at the most recognized databases. Fifty nine studies published in the last thirty years were included and reports and case series were excluded. Conclusions: The Obstructive Sleep Apnea Hypopnea Syndrome is recognized today as a global public health problem. Latin America, specifically Colombia, requires prospective cohort studies that serve as a guideline for the continent's population and that could indicate possible differences compared to the international community regarding early diagnosis and treatment, and its impact in cardiovascular outcomes of these patients.

Structure-function of proteins interacting with the α1 pore-forming subunit of high-voltage-activated calcium channels.

Openings of high-voltage-activated (HVA) calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, HVA calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1) associated with four additional polypeptide chains ß, α2, δ, and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the ß-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of HVA calcium channels.

Tuberculosis pleural asociada con adalimumab, en un paciente con artritis reumatoide / Pleural tuberculosis associated with adalimumab in a patient with rheumatoid arthritis

La tuberculosis constituye, en nuestro medio, una de las enfermedades infecciosas endémicas. Con el advenimiento de las nuevas terapias para el control de la artritis reumatoide,como los inhibidores del factor denecrosis tumoral, la incidencia de casos de reactivación ha aumentado notoriamente. Se presenta el caso de una mujer de 42 años de edad, con disnea, dolor torácico, tos, derrame pleural con líquido pleural tipo exudado linfocítico, con deaminasa de adenosina (ADA) de 55 U-L e identificación de granuloma en la biopsia pleural. Se revisa laliteratura y se hacen recomendaciones.

Tuberculosis (TB) represents one of the endemic infectious diseases in our population. The incidence of reactivate TB cases has grown notoriously with the onset of new therapeutic options for controlling rheumatoid arthritis (RA), such as tumor necrosis factor (TNF) inhibitors. The case of a 42 year old woman is highlighted. Her condition is characterized by shortness ofbreath, chest pain, cough, pleural effusion, linfocitic exudate pleural fluid, ADA 55 U-L and granuloma in pleural biopsy. A review of relevant literature and recommendations are presented.

Daño endotelial y activación del sistema hemostático asociado al uso crónico de cocaína: estudios ex vivo e in vitro / Endothelial damage and activation of the haemostatic system associated to chronic use of cocaine: an ex vivo and in vitro study

Antecedentes: Usuarios crónicos de cocaína tienen riesgo aumentado de presentar infarto de miocardio, angina,muerte súbita y accidentes cerebrovasculares. Aunque la patogenia del daño vascular es mayormente desconocida, se ha encontrado arterioesclerosis prematura y formación de trombos intravasculares. Objetivo: Demostrar evidencia de daño endotelial y activación del sistema hemostático en usuarios crónicos de cocaína. Métodos: Un grupo de 23 pacientes con criterios de dependencia a cocaína DSM-IV; 19 hombres (edad promedio 32 a), con exposición a la droga dentro de 72 h del estudio. Disfunción endotelial se evaluó por enumeración de las células endoteliales circulantes (CEC) y nivel de sICAM . Para activación del sistema hemostático se incluyó: complejos trombina-antitrombina (TAT) y generación de trombina; NAP-2 y RANTES para activación plaquetaria. In vitro, CE en cultivo (HUVEC), se expusieron a plasma de consumidores o controles. Se midió factor von Willebrand (FVW) en el medio y expresión de FvW y factor tisular (FT) sobre las CE. Adhesión plaquetaria estática se evaluó por microscopía. Resultados: En usuarios de cocaína, con respecto a controles, las CEC estaban significativamente elevadas...

Background: chronic cocaine users have an increased risk of developing myocardial infarction, angina, suddendeath and stroke. Although the pathogenesis of this effect is not completely known, premature atheromatosis and intravascular thrombosis appear to be involved.Aim: to provide evidence for the presence of endothelial damage and activation of the haemostatic system in chronic cocaine users. Methods: 23 subjects (19males, overall mean age 32) with DSM-IV criteria for cocaine dependency and exposure to the drug within 72 hours were studied. Endothelial dysfunction was determined by circulating endothelial cell counts (CEC) and sICAM levels. Thrombin-antithrombin complexes (TAT) and thrombin generation were used to characterize haemostatic status. In vitro, platelet activation was studied by NAP-2 and RANTES. EC in culture (HUVEC) were exposed to plasma from cocaine users and controls. Von Willebrand factor was measured in the culture media as well as its expression along with that of tissue factor in EC. Platelet adhesion was evaluated by microscopy. Results: Compared to controls, EC were significantly increased in cocaine users...

Mutations of nonconserved residues within the calcium channel alpha1-interaction domain inhibit beta-subunit potentiation.

Voltage-dependent calcium channels consist of a pore-forming subunit (Ca(V)alpha(1)) that includes all the molecular determinants of a voltage-gated channel, and several accessory subunits. The ancillary beta-subunit (Ca(V)beta) is a potent activator of voltage-dependent calcium channels, but the mechanisms and structural bases of this regulation remain elusive. Ca(V)beta binds reversibly to a conserved consensus sequence in Ca(V)alpha(1), the alpha(1)-interaction domain (AID), which forms an alpha-helix when complexed with Ca(V)beta. Conserved aromatic residues face to one side of the helix and strongly interact with a hydrophobic pocket on Ca(V)beta. Here, we studied the effect of mutating residues located opposite to the AID-Ca(V)beta contact surface in Ca(V)1.2. Substitution of AID-exposed residues by the corresponding amino acids present in other Ca(V)alpha(1) subunits (E462R, K465N, D469S, and Q473K) hinders Ca(V)beta's ability to increase ionic-current to charge-movement ratio (I/Q) without changing the apparent affinity for Ca(V)beta. At the single channel level, these Ca(V)1.2 mutants coexpressed with Ca(V)beta(2a) visit high open probability mode less frequently than wild-type channels. On the other hand, Ca(V)1.2 carrying either a mutation in the conserved tryptophan residue (W470S, which impairs Ca(V)beta binding), or a deletion of the whole AID sequence, does not exhibit Ca(V)beta-induced increase in I/Q. In addition, we observed a shift in the voltage dependence of activation by +12 mV in the AID-deleted channel in the absence of Ca(V)beta, suggesting a direct participation of these residues in the modulation of channel activation. Our results show that Ca(V)beta-dependent potentiation arises primarily from changes in the modal gating behavior. We envision that Ca(V)beta spatially reorients AID residues that influence the channel gate. These findings provide a new framework for understanding modulation of VDCC gating by Ca(V)beta.

Tuberculosis en pacientes con infección por VIH en el Hospital Universitario de San Ignacio, 2002-2006 / Tuberculosis in patients with HIV infection at the Hospital Universitario de San Ignacio, 2002-2006

Introducción. La prevalencia de coinfección por VIH y tuberculosis es alta en los países en vías de desarrollo. El objetivo del estudio fue describir la incidencia, las características clínicas, el tratamiento y el resultado del mismo en pacientes con coinfección por tuberculosis y VIH/sida en el Hospital Universitario de SanIgnacio en Bogotá, Colombia, durante los años 2002 a 2006. Materiales y métodos. Se seleccionaron pacientes con coinfección VIH/sida y tuberculosis. La revisión de las historias clínicas se hizo mediante un instrumento diseñado para la recolección de variables demográficas, clínicas, radiográficas y de la respuesta al tratamiento antituberculoso y antirretroviral. Resultados. Se identificaron 24 pacientes en el programa, de los cuales, 79% eran hombres, con una edad promedio de 30 años. La incidencia anual osciló entre 0,62% y 3,5%. La principal forma de diagnóstico fue por anatomía patológica, en 63% de los casos. Se identificó tuberculosis pulmonar en 37%, extrapulmonar en 42% y diseminada en 21%. El recuento de CD4 en el momento del diagnóstico fue inferior a 200 en 79% de las ocasiones, con un promedio de 113 por mm³. A todos los pacientes se les suministró tratamiento antituberculoso con cuatro medicamentos y se registró una mortalidad de 20% en el grupo de pacientes con seguimiento completo. La mortalidad no se modificó sino a partir del segundo mes de tratamiento (p < 0,04). Discusión y conclusiones. La mortalidad en pacientes con coinfección por tuberculosis y VIH fue alta, con un diagnóstico complicado debido a la baja sensibilidad de la baciloscopia de esputo y del cultivo. Es posible que se requieran medidas de quimioprevención en pacientes con recuentos de CD4 menores de 200.

Background HIV and tuberculosis coinfection prevalence is high in developing countries. The objective of the present study was to describe the incidence, clinical characteristics, treatment and the clinical outcomes in patients with HIV/aids and tuberculosis coinfection at the Hospital Universitario de San Ignacio in Bogotá Colombia, between the years 2002 and 2006. Materials and methods.We selected patients with HIV/aids and tuberculosis coinfection and reviewed the medical charts. Data was collected using a sheet for demographic, clinical and radiographical information, and outcomes of the antituberculous and antiretroviral treatment. Results 24 patients were identified, 79% were male, with an average age of 30 years. Annual incidence had a range between 0.62% and 3.5%. The main diagnostic method was pathological results in 63% of the cases. The anatomical localization was pulmonary in 37%, extrapulmonary in 42% and milliary in 21%. The CD4 count was less than 200 in 79% of the cases, and the average CD4 count was 113 cells per mm3. All the patients had antituberculous treatment with four drugs and the mortality was 20% for the group of patients with a complete follow up. Mortality was not modified until the second month of treatment ( p < 0.04). Discussion and conclusions. Mortality in patients with tuberculosis was high and the diagnosis was difficult due to the low sensitivity of sputum smear and Mycobacterium culture. Patients with CD4 count less than 200 may require chemoprophylaxis.

Prevalence of heparin-induced antibodies in patients with chronic renal failure undergoing hemodialysis.

Heparin-induced thrombocytopenia (HIT) type II is a serious complication of heparin therapy. It presents initially as thrombocytopenia, and is associated with thrombosis in 20-50% of the cases. HIT is related to the presence of heparin-induced antibodies (HIA), which show specificity for the PF4-heparin (PF4-H) complex. The FcgammaRIIa receptor has been suggested to participate in the pathogenic mechanism of HIA. Since patients undergoing chronic hemodialysis (HD) are exposed repeatedly to heparin, we studied the prevalence of HIA and their eventual relationship with thrombocytopenia and/or thrombosis, and the possible participation of the FcgammaRIIa polymorphism. We studied 207 patients with chronic renal failure (CRF) undergoing HD. As a control we included 130 blood donors and 28 patients with CRF without HD. The HIA patients were studied with the use of a PF4-H ELISA. Additionally, in some positive cases for the previous test, a 14C- serotonin release assay (14C-SRA) was performed. The polymorphism FcgammaRIIa H/R131 was studied by polymerase chain reaction (PCR) with allele-specific primers. Thirty-seven patients (17.9%) undergoing HD presented with HIA. The majority of these antibodies were IgG, IgM, and IgA. The HIA investigated presented specificity against the PF4-H complex, but not against PF4 alone (P<0.001). Twelve out of 22 (54.5%) PF4-H antibodies were positive when tested with the 14C-SRA. The distribution of the FcgammaRIIa polymorphism in patients and healthy controls was 42.6% and 41.6% for H/H131, 41% and 48.9% for the H/R131 isoform, and 16.4% and 9.5% for the R/R131 isoform, respectively. No statistically significant difference in the FcgammaRIIa isoform distribution was found. Twenty-nine out of 156 patients (18.5%) presented thrombocytopenia, and 21/207 (12.4%) had thrombosis of the native vein arterio-venous fistula (AVF). We did not find any statistically significant between HIA and thrombocytopenia or thrombosis. An important proportion of patients with CRF undergoing HD developed HIA, but these cases were not associated with thrombocytopenia or thrombosis of AVF. The frequency of the FcgammaRIIa polymorphism did not statistically differ between HIT type II and normal controls.

[Factor V Leiden and prothrombin G20210A among Chilean patients with venous and arterial thrombosis]. / Factor V Leiden y mutación de la protrombina G20210A en pacientes con trombosis venosa y arterial.

BACKGROUND: Factor V Leiden and G20210A mutation of prothrombin gene are two important genetic polymorphisms associated with an increased risk for thrombosis. AIM: To establish the prevalence of factor V Leiden and prothrombin G20210A mutation in the Chilean population and their association to venous and arterial thromboembolism. MATERIAL AND METHODS: A case-control study was conducted where 149 patients with thrombosis (87 with arterial and 62 with venous thrombosis) confirmed by CAT-scan, electrocardiogram and cardiac enzymes or Doppler depending on the case, and 160 healthy blood donors were genetically analyzed for the presence of both polymorphisms. RESULTS: Factor V Leiden mutation was found in 5.4% of patients and in 1.3% of healthy controls (p=0.04). Heterozygosity for G20210A prothrombin mutation was found in 5.4% of patients and in 2.5% of the control group (p=NS). When arterial and venous thrombosis were considered as separate entities, 4.6% of patients with arterial thrombosis and 6.5% with venous thrombosis presented factor V Leiden (p=NS). Likewise, 8.1% of patients with venous thrombosis and 3.5% of patients with arterial thrombosis had G20210A prothrombin mutation (p=NS). CONCLUSIONS: In non selected consecutive Chilean patients with arterial and venous thrombosis the frequency of factor V Leiden and prothrombin G20210A is less than we could expect from their prevalence in the general population.

Folding of active calcium channel beta(1b) -subunit by size-exclusion chromatography and its role on channel function.

Voltage-gated calcium channels mediate the influx of Ca(2+) ions into eukaryotic cells in response to membrane depolarization. They are hetero-multimer membrane proteins formed by at least three subunits, the poreforming alpha(1)-subunit and the auxiliary beta- and alpha(2)delta-subunits. The beta-subunit is essential for channel performance because it regulates two distinct features of voltage-gated calcium channels, the surface expression and the channel activity. Four beta-subunit genes have been cloned, beta(1-4), with molecular masses ranging from 52 to 78 kDa, and several splice variants have been identified. The beta(1b)-subunit, expressed at high levels in mammalian brain, has been used extensively to study the interaction between the pore forming alpha(1)- and the regulatory beta-subunit. However, structural characterization has been impaired for its tendency to form aggregates when expressed in bacteria. We applied an on-column refolding procedure based on size exclusion chromatography to fold the beta(1b)-subunit of the voltage gated-calcium channels from Escherichia coli inclusion bodies. The beta(1b)-subunit refolds into monomers, as shown by sucrose gradient analysis, and binds to a glutathione S-transferase protein fused to the known target in the alpha(1)-subunit (the alpha-interaction domain). Using the cut-open oocyte voltage clamp technique, we measured gating and ionic currents in Xenopus oocytes expressing cardiac alpha(1)-subunit (alpha(1C)) co-injected with folded-beta(1b)-protein or beta(1b)-cRNA. We demonstrate that the co-expression of the alpha(1C)-subunit with either folded-beta(1b)-protein or beta(1b)-cRNA increases ionic currents to a similar extent and with no changes in charge movement, indicating that the beta(1b)-subunit primarily modulates channel activity, rather than expression.