Comparación entre los pacientes con diagnóstico clínico de EPOC vs los confirmados por Espirometría en un hospital de segundo nivel en Bogotá DC, 2011

Introducción: La enfermedad pulmonar obstructiva crónica (EPOC), está caracterizada por la limitación del flujo aéreo, de forma progresiva y casi irreversible, asociada a la reacción inflamatoria atribuida a diferentes factores, principalmente a la exposición al humo de tabaco. Es considerada un problema de salud pública en Colombia y en el mundo, con un aumento acelerado de la condición crónica en la actualidad. Objetivo: Identificar las diferencias sociodemográficas, clínicas y de tratamiento, entre los pacientes con diagnóstico clínico y espirométricos de EPOC vs los pacientes con diagnóstico clínico y descartados por espirometría en el Hospital de Suba. Material y Métodos: Estudio observacional, descriptivo, retrospectivo como un componente exploratorio para comparar los grupos con diagnóstico de EPOC clínico y confirmado o descartado por espirometría, entre Enero y Agosto del 2011. Se utilizó estadística descriptiva para calcular las medidas de tendencia central, los datos cuantitativos se expresaron como la media de la variable ± desviación estándar, y los cualitativos como porcentaje, la t de Student para analizar diferencia de las variables cuantitativas de medias entre grupos y la prueba de Pearson para analizar la relación entre los datos cualitativos para aquellos con valores esperados menores a 5 se aplicó test exacto de Fisher, tuvimos en cuenta un α de 0.05 para el análisis bivariado y medidas de asociación. Todos los análisis se realizaron con el paquete estadístico SPSS 19,0 Versión corporativa. Resultados: De los 398 pacientes, solo 287 cumplían con criterios de inclusión. El promedio de edad del total de los pacientes fue de 70,29 + 11,18 años, y 59,5% de la población fue de sexo femenino. Del total de pacientes evaluados, 171 pacientes (59.6%) se descartó el diagnóstico de EPOC (VEF1/ VEC > 0,70). Al comparar los grupos de pacientes a los que se les confirmo el diagnóstico de EPOC contras los descartados por espirometría se encontró que no hay diferencias estadísticamente significativas entre la edad; en los pacientes con EPOC predomino el sexo femenino (p 0.02); en los factores de riesgo existe clara asociación entre EPOC y la exposición a humo de leña (p <0.001), y en cuanto al tabaquismo solo se encontró asociación con ex fumador (p 0,011). Para analizar las diferencias en el tratamiento se estratifico por las posible combinaciones de inhaladores con o sin teofilina, encontrando una diferencia estadísticamente significativa para los tratamientos de tres inhaladores (p 0,015), dos inhaladores + teofilina (p 0,05), tres inhaladores + teofilina (p <0.001), y en los pacientes no tratados (p <0,001).

Factores asociados a tratamiento quirúrgico en pacientes con obstrucción intestinal por adherencias

El manejo de la obstrucción intestinal por adherencias es un reto para cualquier especialista en Cirugía debido a que existe controversia sobre el alcance del manejo médico y el momento adecuado para llevar el paciente a cirugía para la resolución del cuadro clínico. En el presente trabajo se pretende, identificar los factores asociados a tratamiento quirúrgico en pacientes con obstrucción intestinal por adherencias. Metodología: Se realizó un estudio de casos y controles en una relación de 1:1, con una recolección de muestra estadística de 48 pacientes en cada grupo, entre mayo 2012 y mayo 2014 en el Hospital Universitario Mayor Mederi y en Barrios Unidos. Se consideraron casos los pacientes intervenidos quirúrgicamente por obstrucción intestinal por bridas y controles los pacientes manejados con tratamiento médico. Se evaluaron factores como edad, antecedentes personales patológicos y quirúrgicos, tiempo de evolución del cuadro clínico, hallazgos en imágenes y laboratorio entre otros. Resultados: Se recolectaron un total de 158 pacientes, (78 casos, 80 controles). Ambas poblaciones fueron comparables (p=0.13). Los factores asociados a tratamiento quirúrgico estadísticamente significativos fueron género masculino, presencia de fiebre al ingreso, el hallazgo de engrosamiento de la pared intestinal y de obstrucción de asa cerrada en imágenes diagnósticas (p<0,05). Discusión: Los principales factores asociados para que un paciente con obstrucción intestinal por bridas requiera de manejo quirúrgico son consistentes con literatura. Se requiere la socialización de los resultados para disminuir la morbimortalidad de nuestros pacientes.

Resonancia magnética cardiaca: medidas lineales y volumétricas en adultos sanos

Introducción: La gran mayoría de las medidas de normalidad utilizadas para la interpretación de resonancia cardiaca son extrapoladas de las medidas de ecocardiografía. Los limitados registros de medidas de normalidad se encuentran ajustados en poblaciones extranjeras, no hay registros en latinoamericanos. Objetivo: Determinar las dimensiones cardiacas utilizando resonancia magnética en una población de personas sin antecedente médicos con repercusión cardiaca para lograr una muestra de valores que permitan ajustar las medidas de normalidad utilizadas por nuestro servicio. Materiales y métodos: se analizaron 45 sujetos sanos con edad comprendida entre los 21 y 45 años, las adquisiciones se realizaron utilizando un equipo de RM de 1,5 teslas, el análisis de las imágenes se realizó mediante el programa Cardiac Volume Vx. Se evaluaron múltiples parámetros morfofuncionales a través de análisis estadístico por medio del sistema SPSS versión 23. Resultados: Mediciones obtenidas de ventrículo izquierdo principales fueron volumen diastólico en mujeres de 62 ml +/- 7.1 y en hombres de 65 ml +/- 11.2 y fracción de eyección de 60 % +/- 5 en mujeres y de 62 % +/- 9 en hombres. En ventrículo derecho el volumen diastólico final se encontró 81.8 ml +/- 14.6 en mujeres y 100 ml +/- 24.8 en hombres y fracción de eyección de 53 % +/- 17 en mujeres y de 45 % +/- 12 en hombres. Volumen de fin de diástole de 50 +/- 12.7 ml en mujeres y de 49 ml +/- 19 ml en hombres y fracción de eyección de aurícula izquierda de 55 % +/- 0.08 en mujeres y de 50 % +/- 0.07 en hombres. Volumen de fin de diástole de 44.1 ml +/- 18.5 en mujeres y de 49.2 ml +/- 22.9 en hombres y fracción de eyección de aurícula derecha de 50 % +/- 11 en mujeres y de 45 % +/- 8 en hombres. Se obtuvieron otras medidas lineales y volumétricas adicionales de cavidades cardiacas y de grandes vasos supracardiacos. Conclusiones: se describen los valores de referencia de los parámetros morfofuncionales de las cavidades cardiacas y de vasos supracardiacos. El sexo fue tenido en cuenta como covariable relacionada con la modificación de los parámetros evaluados. Se sugieren variaciones en las medidas de cavidades cardiacas para la población estudiada relacionada con aclimatación crónica a la altitud de la ciudad de Bogotá.

On the time for fold surfaces to order during the crystallization of polyethylene from the melt and its dependence on molecular parameters

New experiments underpin the interpretation of the basic division in crystallization behaviour of polyethylene in terms of whether or not there is time for the fold surface to order before the next molecular layer is added at the growth front. For typical growth rates, in Regime 11, polyethylene lamellae form with disordered {001} fold surfaces then transform, with lamellar thickening and twisting, towards the more-ordered condition found for slower crystallization in Regime 1, in which lamellae form with and retain {201} fold surfaces. Several linear and linear-low-density polyethylenes have been used to show that, for the same polymer crystallized alone or in a blend, the growth rate at which the change in initial lamellar condition occurs is reasonably constant thereby supporting the concept of a specific time for surfaces to attain the ordered {201}) state. This specific time, in the range from milliseconds to seconds, increases with molecular length, and in linear-low-density polymer, for higher branch contents. (c) 2006 Elsevier Ltd. All rights reserved.

Linear nucleation of polymers

The use of high-melting fibres as linear nuclei for quiescent polymeric melts is instrumental in providing the superior mechanical properties of polymeric self-composites. It also has inherent advantages in the elucidation of fundamental aspects of polymeric crystallization and self-organization, not least in allowing systematic microscopic studies of polymeric crystallization from nucleation through to the growth interface. This has demonstrated explicitly that lamellae develop in two distinct ways, for slower and faster growth, depending on whether fold packing has or has not time to order before the next molecular layer is added with only the former leading to banded growth in linear polyethylene. Other gains in understanding concern cellulation and morphological instability, internuclear interference, isothermal lamellar thickening and banded growth being a consequence of the partial relief of initial surface stress. (c) 2006 Elsevier Ltd. All rights reserved.

Structural analysis of PEO-PBO copolymer monolayers at the air-water interface

X-ray reflectivity (XR) and grazing incidence X-ray diffraction (GIXD) have been used to examine an oxyethylene-b-oxybutylene (E23B8) copolymer film at the air-water interface. The XR data were fitted using both a one- and a two-layer model that outputted the film thickness, roughness, and electron density. The best fit to the experimental data was obtained using a two-layer model (representing the oxyethylene and oxybutylene blocks, respectively), which showed a rapid thickening of the copolymer film at pressures above 7 mN/m. The large roughness values found indicate a significant degree of intermixing between the blocks and back up the GIXD data, which showed no long range lateral ordering within the layer. It was found from the electron density model results that there is a large film densification at 7 mN/m, possibly suggesting conformational changes within the film, even though no such change occurs on the pressure-area isotherm at the same surface pressure.

Consistently inconsistent: commercially available starch-based Dysphagia products

Individuals with dysphagia may be prescribed thickened fluids to promote a safer and more successful swallow. Starch-based thickening agents are often employed; however, these exhibit great variation in consistency. The aim of this study was to compare viscosity and the rheological profile parameters complex (G*), viscous (G″), and elastic modulus (G′) over a range of physiological shear rates. UK commercially available dysphagia products at “custard” consistency were examined. Commercially available starch-based dysphagia products were prepared according to manufacturers’ instructions; the viscosity and rheological parameters were tested on a CVOR Rheometer. At a measured shear rate of 50 s−1, all products fell within the viscosity limits defined according to the National Dysphagia Diet Task Force guidelines. However, at lower shear rates, large variations in viscosity were observed. Rheological parameters G*, G′, and G″ also demonstrated considerable differences in both overall strength and rheological behavior between different batches of the same product and different product types. The large range in consistency and changes in the overall structure of the starch-based products over a range of physiological shear rates show that patients could be receiving fluids with very different characteristics from that advised. This could have detrimental effects on their ability to swallow.

Variability of starch-based thickened drinks for patients with dysphagia in the hospital setting

Starch-based thickening agents may be prescribed for patients with dysphagia. Thickened fluids alter variables of the swallow reflex, allowing more time for bolus manipulation without compromising airway closure. This investigation explored the variation in viscosity and physical characteristics of thickened drinks prepared in different media under laboratory conditions and compared the results with those of thickened drinks presented to dysphagic patients in one hospital. The rheological characteristics were tested on a simple plastometer and a Bohlin CVOR rheometer (Malvern Instruments, Worcestershire, UK). Samples prepared to “syrup” consistency both in the laboratory and in the hospitalwere significantly different from each other (P < 0.0001). This was also the case for samples prepared to “custard” consistency. Differences existed not only in viscosity, but drinks prepared in different media produced different rheological matrices. This signifies different viscoelastic behaviors that may effect manipulation in the mouth. From this study, preparation of thickened drinks using starch-based instant thickening powders appears to be a highly variable practice.

Numerical simulation of the Filchner overflow

The plume of Ice Shelf Water (ISW) flowing into the Weddell Sea over the Filchner sill contributes to the formation of Antarctic Bottom Water. The Filchner overflow is simulated using a hydrostatic, primitive equation three-dimensional ocean model with a 0.5–2 Sv ISW influx above the Filchner sill. The best fit to mooring temperature observations is found with influxes of 0.5 and 1 Sv, below a previous estimate of 1.6 ± 0.5 Sv based on sparse mooring velocities. The plume first moves north over the continental shelf, and then turns west, along slope of the continental shelf break where it breaks up into subplumes and domes, some of which then move downslope. Other subplumes run into the eastern submarine ridge and propagate along the ridge downslope in a chaotic manner. The next, western ridge is crossed by the plume through several paths. Despite a number of discrepancies with observational data, the model reproduces many attributes of the flow. In particular, we argue that the temporal variability shown by the observations can largely be attributed to the unstable structure of the flow, where the temperature fluctuations are determined by the motion of the domes past the moorings. Our sensitivity studies show that while thermobaricity plays a role, its effect is small for the flows considered. Smoothing the ridges out demonstrate that their presence strongly affects the plume shape around the ridges. An increase in the bottom drag or viscosity leads to slowing down, and hence thickening and widening of the plume

Stable isotope and modelling evidence for CO2 as a driver of glacial–interglacial vegetation shifts in southern Africa

Atmospheric CO2 concentration is hypothesized to influence vegetation distribution via tree–grass competition, with higher CO2 concentrations favouring trees. The stable carbon isotope (δ13C) signature of vegetation is influenced by the relative importance of C4 plants (including most tropical grasses) and C3 plants (including nearly all trees), and the degree of stomatal closure – a response to aridity – in C3 plants. Compound-specific δ13C analyses of leaf-wax biomarkers in sediment cores of an offshore South Atlantic transect are used here as a record of vegetation changes in subequatorial Africa. These data suggest a large increase in C3 relative to C4 plant dominance after the Last Glacial Maximum. Using a process-based biogeography model that explicitly simulates 13C discrimination, it is shown that precipitation and temperature changes cannot explain the observed shift in δ13C values. The physiological effect of increasing CO2 concentration is decisive, altering the C3/C4 balance and bringing the simulated and observed δ13C values into line. It is concluded that CO2 concentration itself was a key agent of vegetation change in tropical southern Africa during the last glacial–interglacial transition. Two additional inferences follow. First, long-term variations in terrestrial δ13Cvalues are not simply a proxy for regional rainfall, as has sometimes been assumed. Although precipitation and temperature changes have had major effects on vegetation in many regions of the world during the period between the Last Glacial Maximum and recent times, CO2 effects must also be taken into account, especially when reconstructing changes in climate between glacial and interglacial states. Second, rising CO2 concentration today is likely to be influencing tree–grass competition in a similar way, and thus contributing to the "woody thickening" observed in savannas worldwide. This second inference points to the importance of experiments to determine how vegetation composition in savannas is likely to be influenced by the continuing rise of CO2 concentration.

Global vegetation and terrestrial carbon cycle changes after the last ice age

•In current models, the ecophysiological effects of CO2 create both woody thickening and terrestrial carbon uptake, as observed now, and forest cover and terrestrial carbon storage increases that took place after the last glacial maximum (LGM). Here, we aimed to assess the realism of modelled vegetation and carbon storage changes between LGM and the pre-industrial Holocene (PIH). •We applied Land Processes and eXchanges (LPX), a dynamic global vegetation model (DGVM), with lowered CO2 and LGM climate anomalies from the Palaeoclimate Modelling Intercomparison Project (PMIP II), and compared the model results with palaeodata. •Modelled global gross primary production was reduced by 27–36% and carbon storage by 550–694 Pg C compared with PIH. Comparable reductions have been estimated from stable isotopes. The modelled areal reduction of forests is broadly consistent with pollen records. Despite reduced productivity and biomass, tropical forests accounted for a greater proportion of modelled land carbon storage at LGM (28–32%) than at PIH (25%). •The agreement between palaeodata and model results for LGM is consistent with the hypothesis that the ecophysiological effects of CO2 influence tree–grass competition and vegetation productivity, and suggests that these effects are also at work today.

Evaluation of a polynya flux model by means of thermal infrared satellite estimates

We test the ability of a two-dimensional flux model to simulate polynya events with narrow open-water zones by comparing model results to ice-thickness and ice-production estimates derived from thermal infrared Moderate Resolution Imaging Spectroradiometer (MODIS) observations in conjunction with an atmospheric dataset. Given a polynya boundary and an atmospheric dataset, the model correctly reproduces the shape of an 11 day long event, using only a few simple conservation laws. Ice production is slightly overestimated by the model, owing to an underestimated ice thickness. We achieved best model results with the consolidation thickness parameterization developed by Biggs and others (2000). Observed regional discrepancies between model and satellite estimates might be a consequence of the missing representation of the dynamic of the thin-ice thickening (e.g. rafting). We conclude that this simplified polynya model is a valuable tool for studying polynya dynamics and estimating associated fluxes of single polynya events.

Observational evidence for a negative shortwave cloud feedback in middle to high latitudes

Exploiting the observed robust relationships between temperature and optical depth in extratropical clouds, we calculate the shortwave cloud feedback from historical data, by regressing observed and modeled cloud property histograms onto local temperature in middle to high southern latitudes. In this region, all CMIP5 models and observational data sets predict a negative cloud feedback, mainly driven by optical thickening. Between 45° and 60°S, the mean observed shortwave feedback (−0.91 ± 0.82 W m−2 K−1, relative to local rather than global mean warming) is very close to the multimodel mean feedback in RCP8.5 (−0.98 W m−2 K−1), despite differences in the meridional structure. In models, historical temperature-cloud property relationships reliably predict the forced RCP8.5 response. Because simple theory predicts this optical thickening with warming, and cloud amount changes are relatively small, we conclude that the shortwave cloud feedback is very likely negative in the real world at middle to high latitudes.

Morphometric analysis of tracheary elements in four Portulaca species

This paper deals with the morphological features of the tracheary elements of the vegetative organs in four Portulaca species (Portulaca hirsutissima Camb., P. halimoides L., P. wedermannii Poelln. and P. mucronata Link.) occurring in Southeast and Northeast Brazil. The vessel elements are small (< 25 mu m) and with simple perforation plate. The pattern of wall thickening varied from bordered pitting (in roots) to scalariform and helicoidal (stem and leaves). Statistical methods show variation in vessel-element diameter in different vegetative organs; wider elements were observed in roots. Tracheids occurring in leaves of P. hirsutissima and P. wedermannii, have morphological features that are similar to terminal tracheids or tracheoid idiolasts frequently associated with xerophytes. The paedomorphic features (juvenlism) observed here may be related, in part, to aspects of water transport and storage as described in Cactaceae.

Morphological architecture of Actinocephalus (Koern.) sano (Eriocaulaceae-Poales)

Actinocephalus exhibits perhaps more diversity in habit than any other genus of Eriocaulaceae. This variation is largely a result of differences in the arrangement of the paraclades. Based on the analysis of stem architecture of all 25 species of Actinocephalus, the following patterns were established: (1) leaf rosette, with no elongated axis, instead the axillary paraclades originating directly from the short aerial stem, (2) rosette axis continuing into an elongated axis with spirally arranged paraclades, (3) an elongated axis originating from a rhizome, with ramified paraclades, and (4) an elongated axis originating from a short aerial stem, with paraclades arranged in a subwhorl. The elongated axis exhibits indeterminate growth only in pattern 4. Patterns 3 and 4 are found exclusively in Actinocephalus; pattern I occurs in many other genera of Eriocaulaceae, while pattern 2 is also found in Syngonanthus and Paepalanthus. Anatomically, each stem structure (i.e., paraclade, elongated axis, short aerial stem, rhizome) is thickened in a distinctive way and this can be used to distinguish them. Specifically, elongated axes and paraclades lack thickening, thickening of short aerial stems results from the primary thickening meristem and/or the secondary thickening meristem. Thickening of rhizomes results from the activity of the primary thickening meristem. (c) 2008 Elsevier GmbH. All rights reserved.