Quantitative Intensity Harmonization of Dopamine Transporter SPECT Images Using Gamma Mixture Models

PURPOSE: Differences in site, device, and/or settings may cause large variations in the intensity profile of dopamine transporter (DAT) single-photon emission computed tomography (SPECT) images. However, the current standard to evaluate these images, the striatal binding ratio (SBR), does not efficiently account for this heterogeneity and the assessment can be unequivalent across distinct acquisition pipelines. In this work, we present a voxel-based automated approach to intensity normalize such type of data that improves on cross-session interpretation. PROCEDURES: The normalization method consists of a reparametrization of the voxel values based on the cumulative density function (CDF) of a Gamma distribution modeling the specific region intensity. The harmonization ability was tested in 1342 SPECT images from the PPMI repository, acquired with 7 distinct gamma camera models and at 24 different sites. We compared the striatal quantification across distinct cameras for raw intensities, SBR values, and after applying the Gamma CDF (GDCF) harmonization. As a proof-of-concept, we evaluated the impact of GCDF normalization in a classification task between controls and Parkinson disease patients. RESULTS: Raw striatal intensities and SBR values presented significant differences across distinct camera models. We demonstrate that GCDF normalization efficiently alleviated these differences in striatal quantification and with values constrained to a fixed interval [0, 1]. Also, our method allowed a fully automated image assessment that provided maximal classification ability, given by an area under the curve (AUC) of AUC = 0.94 when used mean regional variables and AUC = 0.98 when used voxel-based variables. CONCLUSION: The GCDF normalization method is useful to standardize the intensity of DAT SPECT images in an automated fashion and enables the development of unbiased algorithms using multicenter datasets. This method may constitute a key pre-processing step in the analysis of this type of images.Instituto de Salud Carlos III FI14/00497 MV15/00034Fondo Europeo de Desarrollo Regional FI14/00497 MV15/00034ISCIII-FEDER PI16/01575Wellcome Trust UK Strategic Award 098369/Z/12/ZNetherland Organization for Scientific Research NWO-Vidi 864-12-00

Crystal Structure of Imaginal Disc Growth Factor-2

Imaginal disc growth factor-2 (IDGF-2) is a member of a recently described family of Drosophila melanogaster-soluble polypeptide growth factors that promote cell proliferation in imaginal discs. Although their precise mode of action has not been established, IDGFs cooperate with insulin in stimulating the growth of imaginal disc cells. We report the crystal structure of IDGF-2 at 1.3-A resolution. The structure shows the classical (betaalpha)(8) barrel-fold of family 18 glycosyl hydrolases, with an insertion of an alpha + beta domain similar to that of Serratia marcescens chitinases A and B. However, amino acid substitutions in the consensus catalytic sequence of chitinases give IDGF-2 a less negatively charged environment in its putative ligand-binding site and preclude the nucleophilic attack mechanism of chitin hydrolysis. Particularly important is the replacement of Glu by Gln at position 132, which has been shown to abolish enzymatic activity in chitinases. Nevertheless, a modest conservation of residues that participate in oligosaccharide recognition suggests that IDGF-2 could bind carbohydrates, assuming several conformational changes to open the partially occluded binding site. Thus, IDGFs may have evolved from chitinases to acquire new functions as growth factors, interacting with cell surface glycoproteins implicated in growth-promoting processes, such as the Drosophila insulin receptor.Fil: Varela, Paloma F.. University of Maryland; Estados UnidosFil: Llera, Andrea Sabina. University of Maryland; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Mariuzza, Roy A.. University of Maryland; Estados UnidosFil: Tormo, José. Universidad Autónoma de Madrid; Españ

Efecto de la suplementación energética sobre la degradabilidad de la fibra en rumiantes en pastoreo

Las condiciones climáticas de la Región Pampeana Semiárida, no permiten tener seguridad en la producción forrajera, dificultando la planificación de la alimentación de los rodeos de cría e invernada sobre todo en invierno. La utilización de una Suplementación energética moderada es una práctica habitual con el objetivo de mejorar la dieta de los animales y cubrir déficit forrajeros, pero se desconoce la influencia sobre la digestión de la fibra y la intensidad de los cambios del ambiente ruminal. El objetivo del presente trabajo fue evaluar los cambios en la utilización digestiva de la fibra de distintos substratos lignocelulósicos, y estimar variables del ambiente ruminal, en novillos cuya dieta se basó en pastoreo de avena y diferentes niveles de Suplementación energética. El estudio se realizó en el Campo Experimental de la Facultad de Agronomía de la UNLPam, con 3 novillos Hereford fistulados de rumen que pastoreaban un verdeo de Avena (Avena sativa cv Cristal). Se utilizó un diseño experimental en Cuadrado Latino de 3 animales y 3 tratamientos, suministrando grano de maíz partido luego de un encierre nocturno en cantidades de MS equivalentes al O% (T1), 0,5% (T2) y 1% (T3) del peso vivo del animal. Se incubaron bolsitas de nylon en el rumen durante 72, 48, 24,12,6,3 Y O horas con diferentes fuentes de fibra: rollo de alfalfa (Medicago sativa), pasto llorón (Eragrostis curvula) diferido, el forraje pastoreado (Avena sativa cv Cristal) y Celulosa. Sobre el residuo de las mismas se estimó la degradabilidad efectiva de la Materia Seca (MS) y la degradabilidad efectiva dela fibra en detergente neutro (FDN). También se tomaron muestras de líquido ruminal a las 0,3,6,9,12 Y 18 horas luego del suministro del grano durante 2 días consecutivos, sobre las cuales se midió pH, concentración de amoníaco (NH3) y concentración de ácidos grasos volátiles de cadena corta (AGV). La Degradabilidad Efectiva de la MS y de la FDN de los forrajes mostraron similar comportamiento, con una disminución significativa (p < 0,05) de T3 respecto a T1. En el caso de la celulosa no fue significativa esta disminución de degradabilidad efectiva pero se presento la misma tendencia, atribuyendo este comportamiento en todos los casos a la variación significativa (p < 0,05) de pH que modifica las poblaciones microbianas en rumen al suplementar con niveles crecientes de grano. En el caso del amoníaco su concentración ruminal disminuyó al suplementar (p< 0,05), sin diferencias entre las cantidades de grano aportadas. Los AGV solo mostraron cambios significativos entre T2 y T3. Como conclusión se podría recomendar la suplementación energética con grano molido a niveles de 0,5% del peso vivo como una estrategia para mantener estable el aporte de nutrientes, sin disminuir significativamente la degradabilidad de la dieta base

Mitigating risk through R&D+Innovation: Chile’s national strategy for disaster resilience

With an annual average expense of more than 2,800 million USD, Chile leads the OECD countries with the largest percentage of the GDP spent in disaster losses per year (almost 1.2% GDP). This was the motivation of the Chilean President in 2015 to ask a group of experts to prepare a national Research, Development, and Innovation (R&D+i) strategy for disaster resilience. The strategy was developed by a group, called by the acronym CREDEN, and involved more than 80 experts representing different national stakeholders from the academia, public and private sectors, NGOs, and the armed forces. The work of CREDEN finished December 2016 and produced an R&D+i roadmap composed of five enabling conditions and 14 tasks. The implementation of this strategy demands a total investment of 914 million USD in 20 years, which is expected to have a benefit-cost ratio of 2.32, and annual savings of about $106 million USD. The first stage in this process is the design of a National Institute of R&D+i for Disaster Resilience (ITReND), which will oversee the implementation of the strategy. ITReND’s design was completed in 2017 and its implementation is expected to begin in 2018. This strategy can be considered as an example of how to position R&D+i in the basis of public policy for disaster resilience. Both, the contents of this strategy and its implementation process, have unique aspects and may help guide other disaster-prone countries in their pursuit of larger resilience to the increasing occurrence rate of extreme natural events

Healthcare network operation in Iquique after the 2014, Pisagua earthquake

On April 1st, 2014, the 8.2 Mw Pisagua earthquake affected the population in the north of Chile and generated disruption of services in the region. The largest effects of the earthquake were observed in the city of Iquique, capital of the Tarapaca Region, where more than 80% of the population of the region lives. This research describes the response of the public healthcare network of Iquique after the earthquake, and aims to identify the principal factors contributing to the network resilience during the early response and recovery phase after the earthquake. Despite the large magnitude of the earthquake, the observed structural damage was minor in the five healthcare centers considered (i.e., the regional hospital and 4 Primary Healthcare Attention Centers, PHACs). However, disruption of services in the healthcare network was large and due mainly to the collapse of non-structural components. Overall, the proper response of the healthcare network of Iquique was heavily supported by the PHACs, which largely provided first-aid, containment, and low-complexity attention to the population, allowing the hospital to focus on more complex procedures. The findings of this study suggest that the resilience of the healthcare network system, besides the robustness of the network’s facilities and their critical units, is also highly dependent on the interrelations and interactions between them in early post-earthquake recovery phases

Impact on Chilean hospitals following the 2015 Illapel earthquake

In a post-disaster environment, hospitals play a critical role in healthcare services continuities to the population while effectively coping with eventual losses of functionality. These losses come from physical damage to the facility, loss of utility lifelines, failure in supply chains, and reduction of personnel. However, data describing the detailed performance of hospitals during past earthquakes are scarce. Consequently, following the 2015 Mw 8.3 Illapel earthquake in central Chile, an exhaustive field campaign was carried out in the Coquimbo region to collect substantial perishable data to describe physical damage to hospitals and functionality losses. This study presents first the baseline information obtained in nine surveyed government hospitals, including size, location and type of infrastructure. Then, the seismic impact was analyzed and classified to show the main physical structural and non-structural damage, lifeline interruptions, losses in hospital units, and variations in flow of patients and staff. Transfers, discharges and evacuations of patients that occurred after the event were also reported. We found that the earthquake did not affect strongly the healthcare service despite the fact that most of the structural and non-structural damage was localized in the largest regional hospital. The archival nature of the data collected may deepen our understanding of the post-earthquake healthcare system performance, which is very useful in improving disaster preparation and overall resilience