Estudio de carcinoma medular de tiroides a partir de un caso índice

El carcinoma de tiroides es un tumor infrecuente; constituye menos del 1% de las neoplasias malignas en la población general y el 0, 5%-3% en la edad pediátrica. Existen cuatro tipos: papilar (80%-90% de los casos), folicular (5%-10%), medular (5%) y anaplásico (2%-3%). En el tipo medular, el 80% son esporádicos, y un 20% se asocia a un síndrome hereditario que se divide, fundamentalmente, en tres grupos: neoplasia endócrina múltiple 1, neoplasia endócrina múltiple 2 y carcinoma medular de tiroides familiar. Las formas hereditarias se producen por una mutación en el protooncogén RET, localizado en el brazo largo del cromosoma 10. Se presenta un caso de carcinoma medular de tiroides detectado a raíz de un estudio genético familiar con el propósito de resaltar la importancia del diagnóstico precoz y la intervención de equipos multidisciplinares expertos en esta patología para su manejo y seguimiento. Thyroid cancer is an uncommon type of cancer, accounting less than 1% of all cancers in adults, and 0.5-3% of all cancers in children. There are four different types: papillary carcinoma (80-90% of cases), follicular (5-10%), medullary (5%) and anaplastic cell (2-3%). Eighty per cent of cases of medullary thyroid cancer are sporadic, but 20% are associated with an inherited syndrome that is divided into three groups: multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma. The inherited forms are caused by a disruption in the RET oncogene, which is located in the long arm of chromosome 10. A hereditary case of medullary thyroid carcinoma is presented. It was detected because of a familial genetic study. The purpose of the paper is emphasize the importance of the early diagnosis and the intervention of multidisciplinary teams of experts

Simple approach to mitigate the emission wavelength instability of III-nitride μLED arrays

III-nitride semiconductors and their heterojunctions exhibit intrinsic polarization due to the asymmetry of their wurtzite structure, which determines all the fundamental properties of III-nitride optoelectronics. The intrinsic polarization-induced quantum-confined Stark effect leads to an emission wavelength shift with increasing injection current for III-nitride visible LEDs, forming an insurmountable barrier for the fabrication of a full color display. For instance, a yellow LED designed to produce yellow light emits green or blue light at an elevated current, while a green (blue) LED gives off blue (violet) light with increasing current. This color instability becomes a serious issue for a microdisplay such as the displays for augmented reality (AR)/virtual reality (VR) typically utilized at proximity to the eye, where human eyes are sensitive to a tiny change in light color. It is well-known that an optical mode wavelength for a microcavity is insensitive to injection current. In this work, we have demonstrated an approach to epitaxially integrating microLEDs (green microLEDs as an example, one of the key components for a full color microdisplay) and a microcavity. This allows the emission from the microLEDs to be coupled with the microcavity, leading to a negligible emission wavelength shift with increasing injection current. In contrast, identical microLEDs but without a microcavity show a large emission wavelength shift from 560 nm down to 510 nm, measured under identical conditions. This approach provides a simple solution to resolving the 30-year issue in the field of III-nitride optoelectronics

Towards an improvement in the spectral description of central stars of planetary nebulae

Context. There are more than 3000 known Galactic planetary nebulae, but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics, which will lead to an increase of our understanding of these amazing objects. Aims. We aim to contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods. This observational study is based on Gemini Multi-Object Spectrographs (GMOS) and with the Intermediate Dispersion Spectrograph (IDS) at the Isaac Newton Telescope spectra of 78 CSPN. The objects were selected because they did not have any previous classification, or the present classification is ambiguous. These new high quality spectra allowed us to identify the key stellar lines for determining spectral classification in the Morgan-Keenan (MK) system. Results. We have acquired optical spectra of a large sample of CSPN. From the observed targets, 50 are classified here for the first time while for 28 the existing classifications have been improved. In seven objects we have identified a P-Cygni profile at the He I lines. Six of these CSPN are late O-Type. The vast majority of the stars in the sample exhibit an absorption-Type spectrum, and in one case we have found wide emission lines typical of [WR] stars. We give a complementary, and preliminary, classification criterion to obtain the sub-Type of the O(H)-Type CSPN. Finally, we give a more realistic value of the proportion of CSPN that are rich or poor in hydrogen.Instituto de Astrofísica de La Plat

A simple approach to achieving ultrasmall III-nitride microlight-emitting diodes with red emission

The microdisplays for augmented reality and virtual reality require ultrasmall micro light-emitting-diodes (μLEDs) with a dimension of ≤5 μm. Furthermore, the microdisplays also need three kinds of such μLEDs each emitting red, green, and blue emission. Currently, in addition to a great challenge for achieving ultrasmall μLEDs mainly based on III-nitride semiconductors, another fundamental barrier is due to an extreme difficulty in growing III-nitride-based red LEDs. So far, there has not been any effective approach to obtain high indium content InGaN as an active region required for a red LED while maintaining high optical performance. In this paper, we have demonstrated a selective epitaxy growth approach using a template featuring microhole arrays. This allows us to not only obtain the natural formation of ultrasmall μLEDs but also achieve InGaN with enhanced indium content at an elevated growth temperature, at which it is impossible to obtain InGaN-based red LEDs on a standard planar surface. By means of this approach, we have demonstrated red μLEDs (at an emission wavelength of 642 nm) with a dimension of 2 μm, exhibiting a high luminance of 3.5 × 107 cd/m2 and a peak external quantum efficiency of 1.75% measured in a wafer form (i.e., without any packaging to enhance an extraction efficiency). In contrast, an LED grown under identical growth conditions but on a standard planar surface shows green emission at 538 nm. This highlights that our approach provides a simple solution that can address the two major challenges mentioned above

Nearly lattice-matched GaN distributed Bragg reflectors with enhanced performance

Heavy silicon-doping in GaN generally causes a rough surface and saturated conductivity, while heavily silicon-doped n++-AlGaN with ≤5% aluminum can maintain an atomically flat surface and exhibit enhanced conductivity. Given this major advantage, we propose using multiple pairs of heavily silicon-doped n++-Al0.01Ga0.99N and undoped GaN instead of widely used multiple pairs of heavily silicon-doped n++-GaN and undoped GaN for the fabrication of a lattice-matched distributed Bragg reflector (DBR) by using an electrochemical (EC) etching technique, where the lattice mismatch between Al0.01Ga0.99N and GaN can be safely ignored. By means of using the EC etching technique, the n++-layers can be converted into nanoporous (NP) layers whilst the undoped GaN remains intact, leading to a significantly high contrast in refractive index between NP-layer and undoped GaN and thus forming a DBR. Our work demonstrates that the NP-Al0.01Ga0.99N/undoped GaN-based DBR exhibits a much smoother surface, enhanced reflectivity and a wider stopband than the NP-GaN/undoped GaN-based DBR. Furthermore, the NP-Al0.01Ga0.99N/undoped GaN-based DBR sample with a large size (up to 1 mm in width) can be obtained, while a standard NP-GaN/undoped GaN-based DBR sample obtained is typically on a scale of a few 100 μm in width. Finally, a series of DBR structures with high performance, ranging from blue to dark yellow, was demonstrated by using multiple pairs of n++-Al0.01Ga0.99N and undoped GaN

Optical characterisation of InGaN-based microdisk arrays with nanoporous GaN/GaN DBRs

Optically pumped whispering gallery mode (WGM) lasing has been observed in many freestanding microdisk structures. Dry etching is normally used to fabricate the microdisks, which causes severe sidewall damage, resulting in degradation of lasing performance, especially for ultra-small electrically-injected devices. In this paper, we demonstrate high quality microdisk cavities with 3.5 µm diameter, by combining a selective overgrowth approach and an epitaxial lattice-matched distributed Bragg reflector (DBR), topped with a highly reflective (>99%) dielectric DBR. InGaN polaritons are found to occur in the high-quality microcavities. WGM modes are measured, with the positions in good agreement with finite difference time domain simulations. Furthermore, lasing behaviour is observed with a threshold at 410 µW and a dominant mode at 488 nm

Deficiencia de vitamina D en niños aragoneses sanos

Introducción: la principal acción de la vitamina D es mantener la concentración de calcio y fósforo dentro del rango fisiológico permitiendo el metabolismo normal y la mineralización ósea. Últimamente, se han descrito receptores de vitamina D en muchos tejidos y se ha relacionado la deficiencia de la vitamina D no solo con raquitismo y osteomalacia, sino también con mayor riesgo de diabetes, obesidad, enfermedades cardiovasculares, oncológicas, infecciosas y autoinmunes. Objetivo: el objetivo del estudio fue conocer la concentración de vitamina D en una población pediátrica sana y comprobar sus factores influyentes, así como analizar la situación actual de profilaxis de vitamina D y valorar la eficacia de las recomendaciones actuales. Métodos: se seleccionaron 107 pacientes sanos, de edades comprendidas entre uno y 15 años, que precisaron una analítica sanguínea como preoperatorio de cirugía menor, cuya patología no influyera en los parámetros del estudio. Resultados: la muestra estaba constituida en un 78, 5% por varones y presentaba una media de edad de 7, 17 ± 3, 79 años. La concentración media de vitamina D fue de 26, 07 ± 7, 11 ng/ml y hasta un 72, 9% presentaba niveles insuficientes. Se dividió la muestra en dos grupos: pacientes con hipovitaminosis D y pacientes con niveles óptimos de vitamina D. Se observó en el grupo con hipovitaminosis un predominio de varones, mayor índice de masa corporal y la presencia de fototipos extremos así como provenientes de padres inmigrantes. También presentaban mayor riesgo de hipovitaminosis los que no habían realizado profilaxis durante el primer año de vida. Conclusiones: se pone de manifiesto el alto porcentaje de población infantil sana con déficit de vitamina D y que las recomendaciones actuales de profilaxis no son llevadas a cabo por la población como recomiendan las guías actuales Background: the main action of vitamin D is to maintain the concentration of calcium and phosphorus within the physiological range, allowing normal metabolism and bone mineralization. Vitamin D receptors have recently been described in many tissues, therefore vitamin D deficiency has been related not only to rickets, but also to increased risk of diabetes, obesity, cardiovascular, oncological, infectious and autoimmune diseases. Objective: the aim of the study was to know the vitamin D concentration in a healthy pediatric population and to verify its influential factors, as well as to analyze the current situation of vitamin D prophylaxis and to evaluate the effectiveness of current recommendations. Methods: one hundred and seven healthy patients aged between one and 15 years were selected, who required a blood test as a preoperative minor surgery and whose pathology did not influence the parameters of the study. Results: the sample analyzed had a total of 78.5% males and a mean age of 7.17 ± 3.79 years. Mean values of vitamin D were 26.07 ± 7.11 ng/ml; up to 72.9% had insufficient levels. The sample was divided into two groups: patients with hypovitaminosis D and patients with optimal vitamin D levels. A predominance of males with a higher body mass index, from immigrant parents, and the presence of extreme phototypes were observed in the hypovitaminosis group. There was also a higher risk of hypovitaminosis in those who had not performed prophylaxis during the first year of life. Conclusions: the high percentage of healthy children with vitamin D deficiency is evident, and current recommendations for prophylaxis are not carried out by the population as recommended by current guidelines

The effects of interactions between proline and carbon nanostructures on organocatalysis in the Hajos-Parrish-Eder-Sauer-Wiechert reaction

The non-covalent interactions of S-(-)-proline with the surfaces of carbon nanostructures (fullerene, nanotubes and graphite) change the nucleophilic-electrophilic and acid-base properties of the amino acid, thus tuning its activity and selectivity in the organocatalytic Hajos-Parrish-Eder-Sauer-Wiechert (HPESW) reaction. Whilst our spectroscopy and microscopy measurements show no permanent covalent bonding between S-(-)-proline and carbon nanostructures, a systematic investigation of the catalytic activity and selectivity of the organocatalyst in the HPESW reaction demonstrates a clear correlation between the pyramidalisation angle of carbon nanostructures and the catalytic properties of S-(-)-proline. Carbon nanostructures with larger pyramidalisation angles have a stronger interaction with the nitrogen atom lone pair of electrons of the organocatalyst, thereby simultaneously decreasing the nucleophilicity and increasing the acidity of the organocatalyst. These translate into lower conversion rates but higher selectivities towards the dehydrated product of Aldol addition

Factors associating with differences in the incidence of renal replacement therapy among elderly : data from the ERA-EDTA Registry

Background. The incidence of renal replacement therapy (RRT) in the general population >= 75 years of age varies considerably between countries and regions in Europe. Our aim was to study characteristics and survival of elderly RRT patients and to find explanations for differences in RRT incidence. Methods. Patients >= 75 years of age at the onset of RRT in 2010-2013 from 29 national or regional registries providing data to the European Renal Association-European Dialysis and Transplant Association Registry were included. Chi-square and Mann-Whitney U tests were used to assess variation in patient characteristics and linear regression was used to study the association between RRT incidence and various factors. Kaplan-Meier curves and Cox regression were employed for survival analyses. Results. The mean annual incidence of RRT in the age group >= 75 years of age ranged from 157 to 924 per million age-related population. The median age at the start of RRT was higher and comorbidities were less common in areas with higher RRT incidence, but overall the association between patient characteristics and RRT incidence was weak. The unadjusted survival was lower in high-incidence areas due to an older age at onset of RRT, but the adjusted survival was similar [relative risk 1.00 (95% confidence interval, 0.97-1.03)] in patients from low- and high-incidence areas. Conclusions. Variation in the incidence of RRT among the elderly across European countries and regions is remarkable and could not be explained by the available data. However, the survival of patients in low-and high-incidence areas was remarkably similar.Peer reviewe

The S2 Stream:the shreds of a primitive dwarf galaxy

We present a multi-instrument chemical analysis of the stars in the metal-poor S2 halo stream using both high- and low-resolution spectroscopy, complemented with a re-analysis of the archival data to give a total sample of 62 S2 members. Our high-resolution program provides alpha-elements (C, Mg, Si, Ca and Ti), iron-peak elements (V, Cr, Mn, Fe, Ni), n-process elements (Sr, Ba) and other elements such us Li, Na, Al, and Sc for a subsample of S2 objects. We report coherent abundance patterns over a large metallicity spread (~1dex) confirming that the S2 stream was produced by a disrupted dwarf galaxy. The S2's alpha-elements display a mildly decreasing trend with increasing metallicity which can be interpreted as a "knee" at [Fe/H]<-2. However, even at the high end of [Fe/H], S2's [alpha/Fe] ratios do not climb down from the halo plateau, signaling prehistoric enrichment pattern with minimal SN Ia contribution. At the low metallicity end, the n-capture elements in S2 are dominated by r-process production: several stars are Ba-enhanced but unusually extremely poor in Sr. Moreover, some of the low-[Fe/H] stars appear to be carbon-enhanced. We interpret the observed abundance patterns with the help of chemical evolution models that demonstrate the need for modest star-formation efficiency and low wind efficiency confirming that the progenitor of S2 was a primitive dwarf galaxy.Comment: Submitted to MNRAS. Comments are welcome