Variability in HfO2-based memristors described with a new bidimensional statistical technique.

A new statistical analysis is presented to assess cycle-to-cycle variability in resistive memories. This method employs two-dimensional (2D) distributions of parameters to analyse both set and reset voltages and currents, coupled with a 2D coefficient of variation (CV). This 2D methodology significantly enhances the analysis, providing a more thorough and comprehensive understanding of the data compared to conventional one-dimensional methods. Resistive switching (RS) data from two different technologies based on hafnium oxide are used in the variability study. The 2D CV allows a more compact assessment of technology suitability for applications such as non-volatile memories, neuromorphic computing and random number generation circuits.

3D simulation of conductive nanofilaments in multilayer h-BN memristors via a circuit breaker approach.

A 3D simulation of conductive nanofilaments (CNFs) in multilayer hexagonal-BN memristors is performed. To do so, a simulation tool based on circuit breakers is developed including for the first time a 3D resistive network. The circuit breakers employed can be modeled with two, three and four resistance states; in addition, a series resistance and a module to account for quantum effects, by means of the quantum point contact model, are also included. Finally, to describe real dielectric situations, regions with a high defect density are modeled with a great variety of geometrical shapes to consider their influence in the resistive switching (RS) process. The simulator has been tuned with measurements of h-BN memristive devices, fabricated with chemical-vapour-deposition grown h-BN layers, which were electrically and physically characterized. We show the formation of CNFs that produce filamentary charge conduction in our devices. Moreover, the simulation tool is employed to describe partial filament rupture in reset processes and show the low dependence of the set voltage on the device area, which is seen experimentally.

Twenty-first Century Trends in the Global Epidemiology of Pediatric-Onset Inflammatory Bowel Disease: Systematic Review.

BACKGROUND & AIMS: The incidence of inflammatory bowel disease (IBD) is increasing internationally, particularly in nations with historically low rates. Previous reports of the epidemiology of pediatric-onset IBD identified a paucity of data. We systematically reviewed the global trends in incidence and prevalence of IBD diagnosed in individuals <21 years old over the first 2 decades of the 21st century. METHODS: We systematically reviewed studies indexed in MEDLINE, EMBASE, Airiti Library, and SciELO from January 2010 to February 2020 to identify population-based studies reporting the incidence and/or prevalence of IBD, Crohn's disease, ulcerative colitis, and/or IBD-unclassified. Data from studies published before 2000 were derived from a previously published systematic review. We described the geographic distribution and trends in children of all ages and limiting to very early onset (VEO) IBD. RESULTS: A total of 131 studies from 48 countries were included. The incidence and prevalence of pediatric-onset IBD is highest in Northern Europe and North America and lowest in Southern Europe, Asia, and the Middle East. Among studies evaluating trends over time, most (31 of 37, 84%) studies reported significant increases in incidence and all (7 of 7) reported significant increases in prevalence. Data on the incidence and prevalence of VEO-IBD are limited to countries with historically high rates of IBD. Time trends in the incidence of VEO-IBD were visually heterogeneous. CONCLUSIONS: Rates of pediatric-onset IBD continue to rise around the world and data are emerging from regions where it was not previously reported; however, there remains a paucity of data on VEO-IBD and on pediatric IBD from developing and recently developed countries.

Intra-articular human deciduous dental pulp stem cell administration vs. pharmacological therapy in experimental osteoarthritis rat model.

OBJECTIVE: The aim of the present study was to compare the molecular and morphological effects of diacerein and glucosamine-chondroitin drug treatment and intra-articular injection therapy of human deciduous dental pulp stem cells (hDPSCs) in a rat knee model of induced osteoarthritis (OA). MATERIALS AND METHODS: Thirty-six adult male rats were randomly separated into six groups: Control group (without induction of OA), osteoarthritis group 60 (induction of OA, saline gavage started on day 14 and performed for 60 days, followed by euthanasia), osteoarthritis group (induction of OA and euthanasia after 14 days), diacerein group, glucosamine-chondroitin group, and mesenchymal stem cell group. The drug-treated groups were gavaged with 50 mg/kg of diacerein and 400/500 mg/kg of glucosamine-chondroitin starting on dat 14 for 60 days. The cell therapy-treated group received an intra-articular single dose of 8 × 105 hDPSCs on day 14, and euthanasia was performed after 60 days. Lateral femoral condyles were collected and prepared for immunohistochemistry and light microscopy procedures. RESULTS: The morphological features and immunoexpression of SOX-5, IHH, MMP-8, MMP-13, and Type II collagen were statistically analysed. Our data suggest that hDPSC therapy contributes more actively and effectively in the structural reorganization of lateral femoral condyles. In contrast, the glucosamine-chondroitin sulphate treatment was more effective in inflammatory control, while diacerein showed better results associated with the maintenance of the primordial cartilage. CONCLUSIONS: The positive therapeutic effect of daily administered conventional drugs can be confirmed in a rat model of OA. However, one single dose of locally administered hDPSCs provides significant improvement in tissue regeneration in an OA model.

Intra-articular human deciduous dental pulp stem cell administration vs. pharmacological therapy in experimental osteoarthritis rat model

OBJECTIVE: The aim of the present study was to compare the molecular and morphological effects of diacerein and glucosamine-chondroitin drug treatment and intra-articular injection herapy of human deciduous dental pulp stem cells (hDPSCs) in a rat knee model of induced osteoarthritis OA. MATERIALS AND METHODS: Thirty-six adult male rats were randomly separated into six groups: Control group without induction of OA, osteoarthritis group 60 induction of OA, saline gavage started on day 14 and performed for 60 days, followed by euthanasia, osteoarthritis group induction of OA and euthanasia after 14 days, diacerein group, glucosamine-chondroitin group, and mesenchymal stem cell group. The drug-treated groups were gavaged with 50 mg/kg of diacerein and 400/500 mg/kg of glucosamine-chondroitin starting on dat 14 for 60 days. The cell therapy-treated group received an intra-articular single dose of 8 × 105 hDPSCs on day 14, and euthanasia was performed after 60 days. Lateral femoral condyles were collected and prepared for immunohistochemistry and light microscopy procedures. RESULTS: The morphological features and immunoexpression of SOX-5, IHH, MMP-8, MMP-13, and Type II collagen were statistically analysed. Our data suggest that hDPSC therapy contributes more actively and effectively in the structural reorganization of lateral femoral condyles. In contrast, the glucosamine-chondroitin sulphate treatment was more effective in inflammatory control, while diacerein showed better results associated with the maintenance of the primordial cartilage. CONCLUSIONS: The positive therapeutic effect of daily administered conventional drugs can be confirmed in a rat model of OA. However, one single dose of locally administered hDPSCs provides significant improvement in tissue regeneration in an OA model.

Reproductive Behavior of Copitarsia uncilata (Lepidoptera: Noctuidae).

Copitarsia sp. (Hampson) (Lepidoptera: Noctuidae: Cuculliinae) is a quarantine pest in different countries and affects diverse crops of economic importance in South America. The development of ethological control strategies is an important issue that requires knowing the reproductive behavior of the species involved. Therefore, the aim of this study was to establish the reproductive behavior of Copitarsia uncilata (Burgos & Leiva) and to evaluate the attractiveness of synthetic pheromone compounds under laboratory conditions. Observations of nocturnal reproductive behavior of males and females were performed for 7 days in order to register the courtship, mating, and oviposition time. Once the period of the highest reproductive activity was identified, flight behavior and attraction of virgin males were evaluated in a wind tunnel towards synthetic compounds previously reported as commercial pheromones for Copitarsia species, namely (Z)-tetradec-9-enyl acetate (Z9-14Ac), (Z)-tetradec-9-enol (Z9-14OH), and their mixture (Z9-14Ac + Z9-14OH at 4:1 ratio), in comparison with virgin females and clean air flow. We observed that reproductive behavior occurs during the first third of the scotophase and begins on the second day after adult emergence. Highest proportion of courtship and mating occurs on days 2 and 3 after emergence, and oviposition starts the night immediately after the first mating. Wind tunnel assessments showed that males were highly attracted to calling females compared with the blend of synthetic pheromone compounds, with 89% and 12% of males landing at the source, respectively. Moreover, males also showed a low response to the isolated compounds (Z9-14Ac 14% and Z9-14OH 4%).

Resistive Switching and Charge Transport in Laser-Fabricated Graphene Oxide Memristors: A Time Series and Quantum Point Contact Modeling Approach.

This work investigates the sources of resistive switching (RS) in recently reported laser-fabricated graphene oxide memristors by means of two numerical analysis tools linked to the Time Series Statistical Analysis and the use of the Quantum Point Contact Conduction model. The application of both numerical procedures points to the existence of a filament connecting the electrodes that may be interrupted at a precise point within the conductive path, resulting in resistive switching phenomena. These results support the existing model attributing the memristance of laser-fabricated graphene oxide memristors to the modification of a conductive path stoichiometry inside the graphene oxide.

Reverse Monte Carlo reconstruction algorithm for discrete electron tomography based on HAADF-STEM atom counting.

In this paper, we propose an algorithm to obtain a three-dimensional reconstruction of a single nanoparticle based on the method of atom counting. The location of atoms in three dimensions has been successfully performed using simulations of high-angle-annular-dark-field images from only three zone-axis projections, [110], [310] and [211], for a face-centred cubic particle. These three orientations are typically accessible by low-tilt holders often used in high-performance scanning transmission electron microscopes.

[Urological pathology of lymphatic origin]. / Patología urológica de origen linfático.

OBJECTIVES: Lymphatic disease is a rarely cause of some very unspecific genitourinary manifestations, assuming a diagnostic challenge in most cases. The aim of this paper is to warn about the possible etiology of these urological lymphatic presentations and discuss its management. METHODS: Retrospective review of clinical data in pediatric patients with urological pathology of lymphatic origin between 2008-2014. Three patients, two boys and a girl, were included. The complaints were: redundant prepuce, inguinal scrotal tumor and urinary incontinence. Clinical, diagnosis and treatment protocol is described. RESULTS: The first case is a male with genital lymphedema presented at birth as a redundant prepuce and the subsequent emergence of lower limb lymphedema, treated with compression bandages. The second case, a groin lymphangioma which debuted as a sudden painless inguinal tumor simulating a cord cyst, it was sclerosed and treated with OK- 432. Finally, a preteen who consulted for involuntary leakage of urine, genital lymphedema likely primary cause (lymphodisplasia) or malformation was diagnosed, which improved with two Lipiodol® embolization. CONCLUSIONS: Genitourinary manifestations can be the debut of more complex lymphatic pathology, so it is necessary to consider this cause, uncommon and nonspecific. Its management must be conservative initially by compression bandages, OK-432 or embolization with Lipiodol®.

OBJETIVOS: La patología linfática es infrecuente como causa de manifestaciones genitourinarias inespecíficas, suponiendo un reto diagnóstico en la mayoría de los casos. El objetivo de este trabajo es advertir sobre la posible etiología linfática de estas presentaciones urológicas y discutir su manejo. MATERIAL Y METODOS: Revisión retrospectiva de los datos clínicos de los pacientes pediátricos con patología urológica de origen linfático entre el año 2008-2014. Se incluyeron 3 pacientes, dos niños y una niña. Todos ellos se evaluaron para obtener un diagnóstico fiable. Los motivos de consulta fueron: prepucio redundante, tumoración inguino-escrotal e incontinencia urinaria. Se describe la clínica, el protocolo diagnóstico y el tratamiento de los mismos. CASOS CLINICOS: El primer caso se trata de un lactante varón con un linfedema genital que presentaba un prepucio redundante congénito y la aparición posterior de linfedema en el miembro inferior que es tratado con vendajes compresivos. El siguiente, un linfangioma inguinal que debutó con una tumoración inguinal indolora de aparición súbita simulando un quiste de cordón y tratado mediante esclerosis con OK-432. Por último, una preadolescente que consultó por escapes involuntarios de orina diagnosticada de linfedema genital de probable causa primaria (linfodisplasia) o malformativa que mejoró con dos embolizaciones de Lipiodol®. CONCLUSIONES: Las manifestaciones genitourinarias pueden ser el debut de una patología linfática más compleja, por ello es necesario tener presente esta etiología infrecuente e inespecífica. Su manejo inicialmente debe ser conservador, mediante vendajes compresivos, OK-432 o embolización con Lipiodol®.

Chemical Composition of the Low-Polar Fraction of the Copitarsia uncilata Burgos & Leiva (Lepidoptera: Noctuidae) Eversible Pheromone Gland.

In Colombia, Copitarsia uncilata Burgos & Leiva has been reported as a pest of ornamental flowers. The leafworm causes serious economic losses to farmers because the shipments are intercepted at the detection sites. The identification and subsequent synthesis of the sex pheromone compounds can lead to the use of semiochemicals as an important strategy to complement the pest management. This paper identifies and characterizes the chemical components of the female sexual gland of C. uncilata at three different age stages in order to relate the effect of age on the gland extract composition. Eggs and larvae were collected from commercial crops. The specimens were reared and sexed. Pheromone glands of intact females were excised at (a) 1-2, (b) 3-4, and (c) 5-6 days old. The extracts were analyzed using GC-MS after two extraction time points: 20 min and 8 days. The extracts from the third age stage showed an increase in concentration for 35% of the compounds after 8 days of storage. The relative abundance as a function of the female age showed two trends: an upward trend, where the relative abundances of the compounds increased through the age stages, while some compounds shown a downward trend. Within the first trend, mostly of the compounds were found to be related with infochemicals type structures, where tetradec-9-en-1-yl acetate (within several C-14 long-chain alcohols) is the main one. The 9-14:Ac quadrupled concentration through the ages is possibly related to the increased length of calling period as female moth age.

Patología urológica de origen linfático / Urological pathology of lymphatic origin

Objetivos. La patología linfática es infrecuente como causa de manifestaciones genitourinarias inespecíficas, suponiendo un reto diagnóstico en la mayoría de los casos. El objetivo de este trabajo es advertir sobre la posible etiología linfática de estas presentaciones urológicas y discutir su manejo. Material y métodos. Revisión retrospectiva de los datos clínicos de los pacientes pediátricos con patología urológica de origen linfático entre el año 2008-2014. Se incluyeron 3 pacientes, dos niños y una niña. Todos ellos se evaluaron para obtener un diagnóstico fiable. Los motivos de consulta fueron: prepucio redundante, tumoración inguino-escrotal e incontinencia urinaria. Se describe la clínica, el protocolo diagnóstico y el tratamiento de los mismos. Casos clínicos. El primer caso se trata de un lactante varón con un linfedema genital que presentaba un prepucio redundante congénito y la aparición posterior de linfedema en el miembro inferior que es tratado con vendajes compresivos. El siguiente, un linfangioma inguinal que debutó con una tumoración inguinal indolora de aparición súbita simulando un quiste de cordón y tratado mediante esclerosis con OK-432. Por último, una preadolescente que consultó por escapes involuntarios de orina diagnosticada de linfedema genital de probable causa primaria (linfodisplasia) o malformativa que mejoró con dos embolizaciones de Lipiodol®. Conclusiones. Las manifestaciones genitourinarias pueden ser el debut de una patología linfática más compleja, por ello es necesario tener presente esta etiología infrecuente e inespecífica. Su manejo inicialmente debe ser conservador, mediante vendajes compresivos, OK-432 o embolización con Lipiodol®

Objectives. Lymphatic disease is a rarely cause of some very unspecific genitourinary manifestations, assuming a diagnostic challenge in most cases. The aim of this paper is to warn about the possible etiology of these urological lymphatic presentations and discuss its management. Methods. Retrospective review of clinical data in pediatric patients with urological pathology of lymphatic origin between 2008-2014. Three patients, two boys and a girl, were included. The complaints were: redundant prepuce, inguinal scrotal tumor and urinary incontinence. Clinical, diagnosis and treatment protocol is described. Results. The first case is a male with genital lymphedema presented at birth as a redundant prepuce and the subsequent emergence of lower limb lymphedema, treated with compression bandages. The second case, a groin lymphangioma which debuted as a sudden painless inguinal tumor simulating a cord cyst, it was sclerosed and treated with OK- 432. Finally, a preteen who consulted for involuntary leakage of urine, genital lymphedema likely primary cause (lymphodisplasia) or malformation was diagnosed, which improved with two Lipiodol® embolization. Conclusions. Genitourinary manifestations can be the debut of more complex lymphatic pathology, so it is necessary to consider this cause, uncommon and nonspecific. Its management must be conservative initially by compression bandages, OK-432 or embolization with Lipiodol®

HAADF-STEM atom counting in atom probe tomography specimens: Towards quantitative correlative microscopy.

The geometry of atom probe tomography tips strongly differs from standard scanning transmission electron microscopy foils. Whereas the later are rather flat and thin (<20 nm), tips display a curved surface and a significantly larger thickness. As far as a correlative approach aims at analysing the same specimen by both techniques, it is mandatory to explore the limits and advantages imposed by the particular geometry of atom probe tomography specimens. Based on simulations (electron probe propagation and image simulations), the possibility to apply quantitative high angle annular dark field scanning transmission electron microscopy to of atom probe tomography specimens has been tested. The influence of electron probe convergence and the benefice of deconvolution of electron probe point spread function electron have been established. Atom counting in atom probe tomography specimens is for the first time reported in this present work. It is demonstrated that, based on single projections of high angle annular dark field imaging, significant quantitative information can be used as additional input for refining the data obtained by correlative analysis of the specimen in APT, therefore opening new perspectives in the field of atomic scale tomography.

Growth of Low-Density Vertical Quantum Dot Molecules with Control in Energy Emission.

In this work, we present results on the formation of vertical molecule structures formed by two vertically aligned InAs quantum dots (QD) in which a deliberate control of energy emission is achieved. The emission energy of the first layer of QD forming the molecule can be tuned by the deposition of controlled amounts of InAs at a nanohole template formed by GaAs droplet epitaxy. The QD of the second layer are formed directly on top of the buried ones by a strain-driven process. In this way, either symmetric or asymmetric vertically coupled structures can be obtained. As a characteristic when using a droplet epitaxy patterning process, the density of quantum dot molecules finally obtained is low enough (2 × 10(8) cm(-2)) to permit their integration as active elements in advanced photonic devices where spectroscopic studies at the single nanostructure level are required.

Enfoques y fundamentos para un modelo de rehabilitación ambulatoria en personas con lesión cerebral adquirida / Approaches and foundations for a model of outpatient rehabilitation in people whit acquired brain injury

Introducción: Un porcentaje significativo de personas que adquieren una lesión cerebral necesita programas de rehabilitación ambulatoria. En Chile predomina aún un modelo biomédico de rehabilitación, no obstante, las nuevas guías clínicas recomiendan un abordaje interdisciplinario que considere las necesidades del paciente y su familia. Actualmente existe un vacío respecto a cómo operacionalizar intervenciones eficaces que respondan a este paradigma. Objetivo: Encontrar evidencia que permita el desarrollo y evaluación de enfoques en neurorehabilitación ambulatoria de personas con lesión cerebral adquirida y las posibles metodologías de operacionalización de estos. Metodología: Revisión inductiva y conceptual de la literatura. Resultados: En la literatura chilena no existe evidencia empírica ni desarrollos sistemáticos sobre los fundamentos y la efectividad de los programas de rehabilitación ambulatoria para estas personas. En la literatura internacional se destacan tres enfoques: el enfoque holista, el centrado en el cliente y el basado en la planificación de metas. Si bien tales enfoques permiten guiar las acciones de los equipos, la evidencia de su efectividad, en base al criterio de expertos y pequeños estudios longitudinales y de caso único, es aun limitada. Conclusiones: Esencial a la construcción de identidad de un equipo de rehabilitación es determinar los principios y enfoques que sustente su labor. La complejidad y diversidad de los pacientes en la fase ambulatoria requiere que los equipos posean claros fundamentos para guiar la constante toma de decisiones. Es necesaria la evaluación de la eficacia de los programas de rehabilitación ambulatoria en Chile, desarrollando metodologías acordes a la naturaleza multifactorial del fenómeno.

Introduction: A significant percentage of people who acquire a Brain Injury need outpatient rehabilitation programs. In Chile the rehabilitation field is in a transitional stage. Even though the biomedical model is predominant in rehabilitation, the clinical guidelines have begun to recommend an interdisciplinary approach that considers patients needs and their families. Now-a-days, there is a gap on how to operationalize effective interventions responding to this paradigm. Objectives: To find evidence that sustains the development and assessment of outpatient neurorehabilitation approaches of people with brain injury and, to describe the possible operationalization methodologies of these. Methodology: Inductive and conceptual review of literature. Results: In Chilean Literature does not exist empirical evidence nor systematic developments on the foundations and effectiveness of outpatient rehabilitation programs for people with brain injury. International Literature describes three approaches: holistic, client centered, and goal-based. While such approaches can guide the team actions, the evidence of their effectiveness, based on expert criteria and small longitudinal studies and single case studies is still limited. Conclusions: For the development of a rehabilitation team identity, it is essential to determine the principles and approaches that support their work. Due to complexity and diversity of patients in the ambulatory phase, it is crucial that teams have clear foundations to guide the constant decision making. The evaluation of the effectiveness of ambulatory programs in Chile is a necessity; also it is to develop methodologies according to the nature of the phenomenon.

Aproximación a un protocolo quirúrgico para el manejo de dientes supernumerarios: evaluación de un caso y revisión de la literatura / Approximation to surgical protocol for the management of supernumerary tooth: evaluation of one case and literature review

Introducción: Los dientes supernumerarios (DSN) son anomalías del desarrollo, cuyas manifestaciones típicas suelen ser modificaciones en secuencia y erupción dentaria. Metodología: Se realizo una búsqueda en Medline y Pubmed con criterios de selección definidos entre los años1985 y 2005.Resultados: Se encontraron 13 artículos útiles para la revisión, de los cuales 2 fueron revisiones bibliográficas. Discusión: La prevalencia de DSN rodea al 2%, presentándose principalmente en hombres. No siempre la exéresis de DSN es necesaria por lo que se debe conocer claramente sus indicaciones además de presentar un estudio radiográfico previo detallado. El protocolo quirúrgico exige una descripción y clasificación del DSN para planificar su tratamiento en un equipo multidisciplinario. Su tratamiento quirúrgico presenta generalmente un pronóstico favorable y sus complicaciones se asocian con cierta frecuencia a las estructuras anatómicas vecinas. Conclusión: Este protocolo quirúrgico ayuda a sistematizar los procedimientos terapéuticos para DSN y hacerlos más predecibles (AU)

Introduction: The supernumerary teeth (DSN) are development anomalies, which typical manifestations are sequence and eruption modifications. Methodology: We did a search in Medline and Pubmed with definied criteria of selection between the year 1985and 2005.Results: 13 articles were found useful for the review, of which 2 were literature reviews. Discussion: DSN’s prevalence surrounds 2 %, appearing principally between men. Not always DSN’s exodontiais necessary for what must know clearly his indications and presenting a radiographic previous study. The surgical protocol demands a description and classification of the DSN to plan the treatment in a multidisciplinary team. The surgical treatment presents generally a favorable prediction and it’s complications are associated with certain frequency to the anatomical neighboring. Conclusion: This surgical protocol helps to systematize the therapeutic procedures for DSN and to do them more predecible (AU)

HLA-DRB1*04 and HLA-DQB1*03 association with the atrophic but not with the goitrous form of chronic autoimmune thyroiditis in a Brazilian population.

Autoimmune chronic lymphocytic thyroiditis appears in two forms, goitrous and atrophic. The evidence available is not enough to prove that the goitrous precedes the atrophic form, but immunogenetic analysis suggests that they may be distinct entities. The distribution of HLA class II alleles DRB1* and DQB1* was verified in patients from the region of Campinas, São Paulo, Brazil with both forms of thyroiditis. Ninety-one patients with primary hypothyroidism through autoimmune thyroiditis were classified as goitrous - 54 patients, 42.27 +/- 11.72 years old, having had hypothyroidism for 8.57 +/- 6.63 years - or atrophic - 37 patients, 42.72 +/- 12.01 years old, hypothyroidism for 6.73 +/- 4.07 years. The distribution of class II alleles was determined, DRB1* and DQB1* were genotyped after purifying DNA blood samples using the DNAzol technique, and the low-resolution PCR-SSP system was utilized for determination of generic alleles. Chi-square and Fisher's exact test were utilized to compare the distribution frequency of HLA alleles and the significant p-values were subjected to Bonferroni correction. We have demonstrated that the DRB1*04 allele is associated with autoimmune thyroiditis, and that there are genotypic differences regarding the presentation forms with a strong association between DRB1*04 and DQB1*03 and the atrophic form only.

Limitación a la tolerancia al ejercicio en pacientes con EPOC a la altura de Bogotá (2.640 m). Patrón respiratorio y gasometría arterial en reposo y en ejercicio pico / Exercise limitation in patients with chronic obstructive pulmonary disease at the altitude of Bogota (2640 m). Breathing pattern and arterial gases at rest and peak exercise

OBJETIVO: Describir la respuesta al ejercicio en sujetos normales y en pacientes con enfermedad pulmonar obstructiva crónica (EPOC) en Bogotá (altura: 2.640 m; presión atmosférica: 560 mmHg) y establecer diferencias con los datos publicados de pacientes con dicha enfermedad a nivel del mar. Las personas sanas a esta altura aumentan la ventilación alveolar para atenuar la hipoxemia (presión arterial de CO2: 30 mmHg; presión arterial de O2: 63 mmHg). MATERIAL Y MÉTODO: Se realizó un estudio descriptivo en pacientes con EPOC y en sujetos sanos. La capacidad de ejercicio se determinó con una prueba incremental en un cicloergómetro. RESULTADOS: Se incluyó en el estudio a 16 sujetos sanos y 25 pacientes con EPOC (volumen espiratorio forzado en el primer segundo del 43,3 ñ 13 por ciento). En comparación con los sujetos sanos, en los pacientes con EPOC se observó un aumento de la ventilación minuto en reposo que no se mantuvo adecuadamente en el ejercicio, así como disminución del consumo de oxígeno pico (53,0 ñ 15 por ciento). En ejercicio pico la capacidad inspiratoria disminuyó (-0,62 ñ 0,34 l), la relación ventilación minuto/ventilación voluntaria máxima aumentó y hubo una intensa hipoxemia (presión arterial de O2 de 49,9 ñ 9,9 mmHg). Esta hipoxemia se correlacionó significativamente con el porcentaje del valor predicho del consumo de oxígeno pico (r = 0,60), la fatiga de los miembros inferiores (r = -0,62), el porcentaje predicho de la capacidad inspiratoria pico (r = 0,61) y el porcentaje predicho del volumen corriente pico (r = 0,49). En comparación con los datos publicados a nivel del mar, en los pacientes con EPOC la ventilación minuto en reposo fue mayor, hubo una mayor disminución de la capacidad inspiratoria durante el ejercicio y la hipoxemia fue más grave tanto en reposo como en ejercicio. CONCLUSIONES: En los pacientes con EPOC residentes en Bogotá demostramos intolerancia al ejercicio determinada por limitación ventilatoria e hipoxemia severa. El aumento de la ventilación minuto en reposo, la mayor disminución de la capacidad inspiratoria y la gravedad de la hipoxemia durante el ejercicio fueron las principales diferencias con la EPOC a nivel del mar (AU)

[Exercise limitation in patients with chronic obstructive pulmonary disease at the altitude of Bogota (2640 m). Breathing pattern and arterial gases at rest and peak exercise]. / Limitación a la tolerancia al ejercicio en pacientes con EPOC a la altura de Bogotá (2.640m). Patrón respiratorio y gasometría arterial en reposo y en ejercicio pico.

OBJECTIVE: To describe the response to exercise of normal subjects and patients with chronic obstructive pulmonary disease (COPD) in Bogota, Colombia (altitude: 2640 m; atmospheric pressure: 560 mm Hg) and compare it with data published on COPD patients at sea level. Healthy people increase their minute ventilation to attenuate hypoxemia (PaCO2: 30 mm Hg; PaO2: 63 mm Hg). MATERIAL AND METHOD: A descriptive study was carried out on healthy subjects and COPD patients. Exercise limitation was determined by an incremental test on a cycle ergometer. RESULTS: The study enrolled 16 healthy subjects and 25 COPD patients (forced expiratory volume in 1 second: 43.3% [SD 13%]). Minute ventilation at rest was greater in COPD patients compared with healthy subjects, it was not adequately sustained during exercise, and there was a reduction in peak oxygen uptake (53.0% [15%]). At peak exercise, inspiratory capacity decreased (-0.62 [0.34] L), the ratio of minute ventilation to maximal voluntary ventilation increased, and severe hypoxemia occurred (PaO2: 49.9 [9.9] mm Hg). There was significant correlation between hypoxemia and the percentage of predicted peak oxygen uptake (r=0.60), leg fatigue (r=-0.62), percentage of predicted peak inspiratory capacity (r=0.61), and the percentage of predicted peak tidal volume (r=0.49). Minute ventilation at rest was shown to be higher, there was a greater reduction in the inspiratory capacity during exercise, and hypoxemia was more severe at rest and during exercise for patients with COPD in Bogota, compared with those at sea level. CONCLUSIONS: Patients with COPD living in Bogota were shown to have lower tolerance to exercise evidenced by ventilatory limitation and severe hypoxemia. Increased minute ventilation at rest, greater reduction in inspiratory capacity, and severity of hypoxemia during exercise were the main differences between COPD in Bogota and at sea level.

Mortalidad precoz en el postoperatorio inmediato del trasplante hepático / Premature death in the early postoperative period after a liver transplant

OBJETIVOS: Se han analizado las complicaciones que aparecen en el postoperatorio inmediato del trasplante hepático estudiando su relación con la mortalidad precoz en dicho proceso. MATERIAL v MÉTODOS: Se han revisado de forma retrospectiva los trasplantes hepáticos en adultos realizados en nuestro hospital, confeccionando dos grupos, el I con los pacientes fallecidos y el II con los pacientes que han sobrevivido en el postoperatorio inmediato, viendo la diferencia de incidencia de las complicaciones en ambos grupos y estudiando su significación estadística mediante la prueba de XI para el análisis univariante y mediante una regresión logística para el análisis multivariante. RESULTADOS: En los 827 trasplantes hepáticos estudiados se ha producido la muerte del receptor en 86 casos, 7 casos en quirófano (0,85 por ciento) y 79 casos en el postoperatorio (9,63 por ciento), lo que significa una mortalidad global para la intervención y el postoperatorio inmediato de un 10,4 por ciento. Las complicaciones que hemos evidenciado con significación estadística respecto a la mortalidad en el análisis multivariante son el síndrome postreperfusión, la fibrillación auricular, el fracaso renal agudo y la presencia de infección. CONCLUSIONES: Sólo una de estas complicaciones es específica del trasplante hepático: el síndrome postreperfusión, las otras son propias de cualquier paciente gravemente enfermo, y prácticamente todas conducen a un aumento de las infecciones, que es la causa más frecuente de fallecimiento en el postoperatorio inmediato. (AU)