Barrett's esophagus: Ten years of experience at a tertiary care hospital center in Mexico. / Esófago de Barrett: experiencia de 10 años en un centro de tercer nivel en México.

INTRODUCTION: The prevalence of Barrett's esophagus has been calculated at between 1.3 and 1.6%. There is little information with respect to this in Mexico. AIM: To determine the frequency and characteristics of Barrett's esophagus in patients that underwent endoscopy at a national referral center, within a 10-year time frame. MATERIAL AND METHODS: The databases of the pathology and gastrointestinal endoscopy departments of the Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" were analyzed, covering the period of January 2002 to December 2012. Patients with a histologic diagnosis of Barrett's esophagus were included. The variables of age, sex, the presence of dysplasia/esophageal adenocarcinoma, Barrett's esophagus length, and follow-up were analyzed. RESULTS: Of 43,639 upper gastrointestinal endoscopies performed, 420 revealed Barrett's esophagus, corresponding to a frequency of 9.6 patients for every 1,000 endoscopies. Of those patients, 66.9% (n=281) were men, mean patient age±SD was 57.2±15.3 years, 223 patients (53%) presented with long-segment Barrett's esophagus, and 197 (47%) with short-segment Barrett's esophagus. Dysplasia was not present in 339 patients (80.7%). Eighty-one (19.3%) patients had some grade of dysplasia or cancer: 48/420 (11.42%) presented with low-grade dysplasia, 20/420 (4.76%) with high-grade dysplasia, and 13/420 (3.1%) were diagnosed with esophageal cancer arising from Barrett's esophagus. Mean follow-up time was 5.6 years. CONCLUSIONS: The frequency of Barrett's esophagus was 9.6 cases for every 1,000 upper gastrointestinal endoscopies performed. Dysplasia was not documented in the majority of the patients with Barrett's esophagus and they had no histopathologic changes during follow-up. A total of 19.3% of the patients presented with dysplasia or cancer.

Impact of dust and smoke mixing on column-integrated aerosol properties from observations during a severe wildfire episode over Valencia (Spain).

The most destructive wildfire experienced in Spain since 2004 occurred close to Valencia in summer 2012. A total of 48.500ha were affected by two wildfires, which were mostly active during 29-30 June. The fresh smoke plume was detected at the Burjassot measurement station simultaneously to a severe dust episode. We propose an empirical method to evaluate the dust and smoke mixing and its impact on the microphysical and optical properties. For this, we combine direct-sun measurements with a Cimel CE-318 sun-photometer with an inversion methodology, and the Mie theory to derive the column-integrated size distribution, single scattering albedo (SSA) and asymmetry parameter (g). The mixing of dust and smoke greatly increased the aerosol load and modified the background aerosol properties. Mineral dust increased the aerosol optical depth (AOD) up to 1, while the smoke plume caused an extreme AOD peak of 8. The size distribution of the mixture was bimodal, with a fine and coarse modes dominated by the smoke particles and mineral dust, respectively. The SSA and g for the dust-smoke mixture show a marked sensitivity on the smoke mixing-ratio, mainly at longer wavelengths. Mineral dust and smoke share a similar SSA at 440nm (~0.90), but with opposite spectral dependency. A small dust contribution to the total AOD substantially affects the SSA of the mixture, and also SSA at 1020nm increases from 0.87 to 0.95. This leads to a different spectral behaviour of SSA that changes from positive (smoke plume) to negative (dust), depending on the dust and smoke mixing-ratio.

UVER and UV index at high altitude in Northwestern Argentina.

Measurements of ultraviolet erythemal radiation (UVER) made during two years at three sites located at altitudes over 1000ma.s.l. in Northwestern Argentina (Salta, San Carlos, and El Rosal) have been used to estimate and analyze the UV Index (UVI) and the cumulative doses at these locations. For the UVER irradiance, data of January (maximum values) and June (minimum values) have been analyzed as representative of the year for all locations. The UVI reaches extreme (>11) values in >20% of the analyzed days in Salta (1190ma.s.l.), while these are reached in San Carlos (1611ma.s.l.) and El Rosal (3355ma.s.l.) in >40% of the analyzed days. Finally, the cumulative doses over an average year have also been studied for each location. The doses received during austral summer and autumn are of the same order, and represent one third of the annual dose, while the doses received during austral winter and spring represent one sixth of the annual dose approximately.

Determination of minimal erythema dose and anomalous reactions to UVA radiation by skin phototype.

BACKGROUND: Phototesting is a technique that assesses the skin's sensitivity to UV radiation by determining the smallest dose of radiation capable of inducing erythema (minimal erythema dose [MED]) and anomalous responses to UV-A radiation. No phototesting protocol guidelines have been published to date. METHODOLOGY: This was a multicenter prospective cohort study in which 232 healthy volunteers were recruited at 9 hospitals. Phototests were carried out with solar simulators or fluorescent broadband UV-B lamps. Each individual received a total of 5 or 6 incremental doses of erythemal radiation and 4 doses of UV-A radiation. The results were read at 24hours. RESULTS: At hospitals where solar simulators were used, the mean (SD) MED values were 23 (8), 28 (4), 35 (4), and 51 (6) mJ/cm(2) for skin phototypes i to iv, respectively. At hospitals where broadband UV-B lamps were used, these values were 28 (5), 32 (3), and 34 (5) mJ/cm(2) for phototypes ii to iv, respectively. MED values lower than 7, 19, 27, and 38 mJ/cm(2) obtained with solar simulators were considered to indicate a pathologic response for phototypes I to IV, respectively. MED values lower than 18, 24, and 24mJ/cm(2) obtained with broadband UV-B lamps were considered to indicate a pathologic response for phototypes ii to iv, respectively. No anomalous responses were observed at UV-A radiation doses of up to 20J/cm(2). CONCLUSIONS: Results were homogeneous across centers, making it possible to standardize diagnostic phototesting for the various skin phototypes and establish threshold doses that define anomalous responses to UV radiation.

Ten years of measured UV Index from the Spanish UVB Radiometric Network.

An analysis is made of the UV Index (UVI) obtained from the ultraviolet erythemal solar radiation (UVER) data measured by the Spanish UVB Radiometric Network between the years 2000 and 2009. Previously, the daily UVI has been evaluated using two different criteria: (a) the value corresponding to solar noon; and (b) the daily maximum value. The mean percentage of agreement is 92% if we consider the cases for which the difference is zero or one UVI unit. These results are similar to those obtained in a previous work where only 2 years were analyzed. In all the stations the UVI reaches very high values (8-10) in spring-summer, and the very high and extreme (≥ 11) UVI values are more dependent on the continental effect than on the latitude effect. From the UVI values it is possible to classify the stations into four groups: Coastal stations, Continental stations (more than 200 km from the coast), Southern stations (Coastal stations but with similar values of UVI as the Continental ones due to their low latitude) and Canary Islands stations (1400 km southwest from the Iberian Peninsula thus lower latitude). The monthly mean maximum of UVI is reached in July due to the annual evolution of the total ozone column. This value corresponds, for a skin phototype II, to three times the minimal erythemal dose (MED) in an hour in a Coastal station, 3.5 MEDs in an hour measured in a Continental or Southern station and up five MEDs in an hour in the Izaña station (Canary Islands). The cumulative dose on a horizontal plane over an average year has been calculated for each station. More than 40% of the annual dose is received in summer, about 35% in spring, more than 11% in autumn and less than 10% in winter except for the stations in the Canary Islands where the difference between seasons is less significant.

Modelling of the UV Index on vertical and 40° tilted planes for different orientations.

In this study, estimated data of the UV Index on vertical planes are presented for the latitude of Valencia, Spain. For that purpose, the UVER values have been generated on vertical planes by means of four different geometrical models a) isotropic, b) Perez, c) Gueymard, d) Muneer, based on values of the global horizontal UVER and the diffuse horizontal UVER, measured experimentally. The UVER values, obtained by any model, overestimate the experimental values for all orientations, with the exception of the Perez model for the East plane. The results show statistical values of the MAD parameter (Mean Absolute Deviation) between 10% and 25%, the Perez model being the one that obtained a lower MAD for all levels. As for the statistic RMSD parameter (Root Mean Square Deviation), the results show values between 17% and 32%, and again the Perez model provides the best results in all vertical planes. The difference between the estimated UV Index and the experimental UV Index, for vertical and 40° tilted planes, was also calculated. 40° is an angle close to the latitude of Burjassot, Valencia, (39.5°), which, according to various studies, is the optimum angle to capture maximum radiation on tilted planes. We conclude that the models provide a good estimate of the UV Index, as they coincide or differ in one unit compared to the experimental values in 99% of cases, and this is valid for all orientations. Finally, we examined the relation between the UV Index on vertical and 40° tilted planes, both the experimental and estimated by the Perez model, and the experimental UV Index on a horizontal plane at 12 GMT. Based on the results, we can conclude that it is possible to estimate with a good approximation the UV Index on vertical and 40° tilted planes in different directions on the basis of the experimental horizontal UVI value, thus justifying the interest of this study.

UV Index on tilted surfaces.

Solar ultraviolet erythemal irradiance (UVER) has been studied on inclined planes with different orientations in Valencia, Spain. To do this a platform was designed that could turn through 90 degrees on its own axis. The radiometers were inclined at an angle close to the latitude of Valencia (39.5 degrees N). Using two timers the platform could be turned through 90 degrees every 5 min. On clear or partially cloudy days, including those with different turbidity values, it was observed that the UVER showed a maximum at 1200 h GMT, very close to solar noon, in the north and south positions, while the maximum for east and west orientations was found at approximately one hour before and one hour after midday respectively. It was also observed how the irradiance for the south orientation was greater and for the north was less than for the horizontal plane, as well as the opposite performances of the east and west orientations, for four days close to the summer and winter solstices and each equinox. Some experimental results were also compared with the results from the SMARTS2.9 model for the same conditions. It was found that the model frequently overestimated the experimental data. With respect to the maximum calculated UV Index in the different planes this was always higher for the south orientation than for the north, while it was similar for east and west orientations throughout the year. Finally the accumulated erythemal dosage for the considered period was obtained as a function of phototype and orientation, confirming that the accumulated erythemal dosage decreased by around 37% in the north orientation compared to the horizontal value, while in the south position it was only 6% less and some 20% and 15% less in the east and west positions, respectively.

The UV Index on the Spanish Mediterranean coast.

An analysis is made of measured ultraviolet erythemal solar radiation (UVER) data recorded during the year 2003 by the networks of the Catalan Weather Service and the Environment Department of Valencia (both on the Spanish Mediterranean coast). Results show a latitudinal variation at sea level, of 3-4% per degree and an increase with altitude of 10% per km. Based on these data the UV Index has been evaluated for the measuring stations. The maximum experimental value of the UV Index was around 9 during the summer, although higher values were recorded at two stations, one at the highest elevation and the other at the lowest latitude. The annual accumulated doses of irradiation on a horizontal plane have been presented as well as the evolution through the year in units of energy, Standard Erythemal Doses and Minimum Erythemal Doses according to different phototypes. Lastly, the UV Index forecast, determined with a multiple scattering radiative transfer model, has been analyzed. Total agreement or only one unit of difference between measured and modelled values was found in 94% of cloud-free cases.

Determination of the Atmospheric-Water-Vapor Content in the 940-nm Absorption Band by Use of Moderate Spectral-Resolution Measurements of Direct Solar Irradiance.

We have analyzed three methods that can be used to determine the integrated water vapor of the atmosphere in the 940-nm band by means of modeled and measured direct solar spectral irradiance. The experimental irradiance data were obtained with a commercial LI-COR 1800 spectroradiometer, based on a monochromator system, of high to moderate spectral resolution (6 nm) in the 300-1100-nm range. The modeled data are based on monochromatic approaches to determine atmospheric transmittance constituents; for those of water vapor we used the lowtran7 model. The first method is a curve-fitting procedure that makes use of the entire shape band absorption information to retrieve a unique water-vapor value. The second method makes use of the monochromatic approach of the absorption transmittance formula to determine the amount of water vapor at each wavelength of the absorption band, and the third method is the classic differential absorption technique suitably applied to our data. Spectral analysis showed the advantages and disadvantages of each method, such as problems linked to the various spectral resolutions of the experimental and the modeled data, the width of the spectral range used to define the water-vapor absorption band, and the dependence of the retrieval on the choice of the two selected wavelengths in the last-named technique. All these problems were considered so they could be avoided or minimized and the associated errors estimated. We used the methods to determine water-vapor values for the period from March to November 1995 at a rural station in Vallodolid, Spain, allowing for the evaluation of the differences in real monitoring conditions. Finally, the contribution of continuum absorption was also evaluated, yielding lower water-vapor values between 13 and 30%. These differences were considerably greater than those that were due to the problems that we have just enumerated.