Chemical communication in anurans: an integral perspective from behavioral, morphological and chemical aspects in two species of Hypsiboas (Amphibia: Anura: Hylidae)

La piel de los anfibios es un órgano dinámico con una enorme diversidad de funciones. Una característica compartida por prácticamente todas las especies de anfibios es la presencia de dos tipos de glándulas dérmicas, mucosas y serosas. A pesar de la similitud estructural, estas glándulas pueden presentar una gran variabilidad morfológica alcanzando un alto grado de especialización en el cumplimiento de dos funciones, la comunicación química y la defensa contra predadores. Desde un aspecto bioquímico, el análisis de las secreciones glandulares posee un potencial enorme dado la diversidad de compuestos. Los estudios desarrollados en algunos de ellos (i.e., péptidos, alcaloides, aminas biogénicas) permite tener una idea aproximada de la variación estructural y funcional. Sin embargo, es limitado el conocimiento que se tiene sobre la química de los compuestos volátiles y de los componentes secretados por las glándulas de la piel sexualmente dimórficas (SDSGs); fuente potencial de feromonas. Tradicionalmente los estudios de comunicación en los anuros se focalizaron en el análisis de las señales acústicas, aunque existían reportes aislados de la participación de otras señales (i.e., visual, química, táctil) en algunas especies. Los trabajos recientes muestran que estas señales tienen una distribución taxonómica mucho mayor a la considerada inicialmente, en tanto que la co-ocurrencia de distintas señales sugieren la existencia de comunicación multimodal en algunas especies. En la presente tesis se abordaron aspectos morfológicos, químicos y comportamentales de las secreciones glandulares en dos especies de Hypsiboas, considerando un contexto reproductivo en H. punctatus y un contexto defensivo en H. pulchellus. Se analizó la estructura y la ultraestructura de la piel de las regiones mental, lateral, dorsal y ventral en machos y hembras de H. punctatus. Se identificaron dos tipos de SDSGs, en las regiones mental y lateral de los machos, representando el primer caso de co-ocurrencia de diferentes SDSGs en una misma especie de anuro. A partir de estos resultados se caracterizó la variación estructural e histoquímica, y se estudió la evolución de las glándulas mentales y laterales en 28 especies de Cophomantini, incluyendo representantes de prácticamente todos los grupos de especies. La ocurrencia de estas glándulas, al igual que la variación morfológica, presenta una distribución taxonómica compleja con diferentes niveles de homoplasia. A partir del análisis de las secreciones de las glándulas dorsales de machos y hembras se determinó la estructura primaria de 13 péptidos y se identificaron dos compuestos relaciones con alcaloides. Se identificó un péptido presente exclusivamente en las secreciones de las glándulas mental y lateral de los machos. Los estudios comportamentales en el campo y en condiciones controladas de laboratorio, mostraron que los machos de H. punctatus son territoriales y poseen un repertorio vocal complejo con al menos siete cantos diferentes asociados a contextos particulares. Las hembras elegirían a los machos en base a la información de las señales acústicas y químicas, lo que sugiere la existencia de comunicación multimodal en esta especie. El estudio morfológico e histoquímico de las glándulas de H. pulchellus evidenció la presencia de las dos glándulas comunes de los anfibios (mucosas y serosas). Sin embargo, los análisis de estructura, ultraestructura y de los mecanismos fisiológicos de descarga permiten inferir que las glándulas serosas cumplirían diversas funciones, entre ellas almacenar los componentes volátiles secretados en situaciones de estrés. Estas glándulas presentan una mayor concentración en la región escapular, lo que podría relacionarse con estrategias defensivas. A partir del análisis de las secreciones de las glándulas dorsales de machos y hembras se determinó la estructura primaria de 17 péptidos y se identificaron dos compuestos relaciones con alcaloides. Las secuencias peptídicas de H. pulchellus e H. punctatus presentan una gran variabilidad. Estos compuestos no fueron publicados anteriormente, aunque algunos de los péptidos presentaron una gran similitud con los descriptos en otras especies de Cophomantini. Se compararon las secuencias de todos los péptidos identificados hasta el momento en esta tribu. El solapamiento de las secuencias de los péptidos de H. pulchellus e H. punctatus con partes de péptidos mayores de otras especies sugiere la existencia de endopeptidasas específicas. Se caracterizó la fracción volátil de las secreciones de la región dorsal y lateral en H. pulchellus e H. riojanus. Se identificaron 42 compuestos (40 en H. pulchellus y 37 en H. riojanus) pertenecientes a nueve grupos funcionales, lo que constituye la mayor diversidad de compuestos volátiles identificados en una especie de anfibio. Los diferentes componentes tendrían distinto origen y función.The skin of amphibians is a dynamic organ with diverse functions. Almost all the species of this group of vertebrates possess two types of dermal glands, mucous and serous glands. Despite the structural similarities within each glandular type, they may have a great morphological variation getting a high degree of specialization related to chemical communication and defense against predators. From a biochemical perspective, and given the high diversity of their compounds, researches on the glandular secretions have an enormous potential. In particular, the studies performed on some of them (i.e., peptides, alkaloids, biogenic amines) allowed a general understanding of their structural and functional diversity. However, knowledge of the chemical composition of the volatile secretions, as well as from the secretion of sexually dimorphic skin glands (SDSGs; a likely source of sexual pheromones) in anurans, is very limited. Although there are isolated reports of the existence of different signals used for communication in some species (i.e., visual, chemical, tactile), studies of communication in anurans have traditionally focused in the analysis of acoustic signals. Nonetheless, recent investigations show that those considered rare signals have a wide taxonomic distribution, whereas the simultaneous occurrence of some of them suggest the existence of multimodal communication in several species. In this thesis are examined morphological, chemical and behavioral aspects from de glandular secretions of two species of Hypsiboas, considering a reproductive context in H. punctatus, and a defensive context in H. pulchellus. The structure and ultrastructure of skin from mental, lateral, dorsal, and ventral regions, was examined in males and females of H. punctatus. Two types of SDSGs were identified en mental and lateral regions of males. These results represent the first case of co-occurrence of different SDSGs in a single species. The structural and histochemical variation, as well as the evolution, of mental and lateral glands was analyzed in Cophomantini from samples of 28 species including at least a representative of almost all group of species of this clade. The occurrence of mental and lateral glands and their morphological variation have an intricate taxonomic distribution with different levels of homoplasy. Thirteen peptides and two compounds related with alkaloids were identified from dorsal secretions of males and females. One peptide was found exclusively from mental and lateral secretions of males. Behavioral studies performed in the field and under laboratory controlled conditions showed that males are territorial. They emit at least seven different type of calls associated to specific biological contexts. Females would choose their mates on acoustic and chemical signals, which suggest the existence of multimodal communication in this species. Morphological and histochemical studies of the skin of H. pulchellus revealed the presence of the two typical mucous and serous glands of amphibians. However, a detailed structural and ultrastructural analysis, as well as the physiological assessment of the release mechanism of gland secretion, suggests that serous glands have several functions. One of these functions is to accumulate, and under stress situations, secrete volatile compounds. These glands are highly concentrated in the scapular region, which is possible related to defensive strategies. Seventeen peptides and two compounds related with alkaloids were identified from dorsal secretions of males and females. The peptide sequences of H. pulchellus and H. punctatus are highly variable. These compounds have not been published before, but some of them showed great similarities with peptides described in other species of Cophomantini. All peptides reported so far in species of this tribe were compared through sequence alignments. The sequences of H. pulchellus and H. punctatus overlapped longer sequences of other species suggesting the existence of specific endopeptidase. The volatile secretions of H. pulchellus and H. riojanus were characterized from dorsal and lateral skin by a simulated stress situation. Forty-two compounds (40 in H. pulchellus and 37 in H. riojanus) from nine different functional groups were identified in all samples. This represent the highest number of volatile compounds identified in a species of amphibian. The components would have different origin and functions.Fil:Brunetti, Andrés E.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Diagnostic utility of Restriction Spectrum Imaging in the characterization of the peritumoral brain zone in glioblastoma: Analysis of overall and progression-free survival

Purpose We studied the ability of Restriction Spectrum Imaging (RSI), a novel advanced diffusion imaging technique, to estimate levels of cellularity in different glioblastoma regions, evaluated their prognostic value compared with established clinical diffusion metrics such as fractional anisotropy (FA) and mean diffusivity (MD). Methods Forty-two patients with untreated glioblastoma, IDH-wildtype, were examined with an advanced MRI tumor protocol. The region of interest (ROI) was obtained from the contrast-enhancing part of tumor and the peritumoral brain zones and then co-registered with RSI-cellularity index, FA and MD maps. Histogram parameters of diffusion metrics were assessed for all ROI locations and compared to MGMT promoter methylation status and survival. The ability of RSI-cellularity index, FA, and MD to stratify survival and were assessed by Cox proportional hazard regression, adjusted for significant clinical predictors. Results The highest RSI-cellularity index was measured in contrast-enhancing tumor core with a negative gradient from tumor core to the periphery of peritumoral zone with predictive accuracy 81 % (P < 0.001). Shorter overall survival was significant associated with higher RSI-cellularity index (hazard ratio (HR) 3.6, 95 % confidence interval (CI) 1.3−9.5, P = 0.002) with synchronal decrease in MD (HR 0.31, 95 %CI 0.1−0.8, P = 0.008) in the contrast-enhanced tumor core. This association was also consistent for RSI-cellularity index value measured in the peri-enhancing zone (HR 3.6, 95 % CI 1.0−12.3, P = 0.041). No statistically significant differences were noted between RSI-cellularity index, FA, nor MD and MGMT promoter methylation. Conclusion RSI-cellularity index may be used as prognostic biomarker to improve risk stratification in patients with glioblastoma

Diversity and evolution of the parotoid macrogland in true toads (Anura: Bufonidae)

Skin glands in amphibians are either distributed throughout the skin or aggregated in multiglandular structures such as the parotoids typical of most species of Bufonidae. Although many early divergent and derived bufonids lack a discrete parotoid in the postorbital-supratympanic (PoSt) region, they have a great macroscopic diversity in the skin morphology of this region. To understand the origin and evolution of this diversity, in particular of the parotoids, we describe the histomorphology of the skin of the PoSt and dorsal regions in 17 species of bufonids, with or without external evident parotoid, and compare it with previously published descriptions. The survey results in 27 characters that were optimized on a phylogenetic hypothesis of Bufonidae. Our results reveal that the PoSt region has a noteworthy morphological diversity of types of glands, spatial organization and differences in the secretion products. Some morphological characters represent putative synapomorphies of internal clades of Bufonidae and are related to the progressive differentiation towards defined structures (macroglands, parotoids). These morphological results, along with published information on the toxicity of the skin secretions and defensive behaviours in some representative species, allow us to infer possible relationships between these features.Fil: Ódonohoe, M. E. Ailin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de Anfibios; ArgentinaFil: Luna, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Regueira, Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de Anfibios; ArgentinaFil: Brunetti, Andrés Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidade de Sao Paulo; BrasilFil: Basso, Nestor Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Lynch, John D.. Instituto de Ciencias Naturales de Colombia; ColombiaFil: Pereyra, Martín Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Hermida, Gladys Noemí. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de Anfibios; Argentin

Analysis of shared common genetic risk between amyotrophic lateral sclerosis and epilepsy

Because hyper-excitability has been shown to be a shared pathophysiological mechanism, we used the latest and largest genome-wide studies in amyotrophic lateral sclerosis (n = 36,052) and epilepsy (n = 38,349) to determine genetic overlap between these conditions. First, we showed no significant genetic correlation, also when binned on minor allele frequency. Second, we confirmed the absence of polygenic overlap using genomic risk score analysis. Finally, we did not identify pleiotropic variants in meta-analyses of the 2 diseases. Our findings indicate that amyotrophic lateral sclerosis and epilepsy do not share common genetic risk, showing that hyper-excitability in both disorders has distinct origins

Management and outcome of mechanically ventilated patients after cardiac arrest

Introduction: The aim of this study was to describe and compare the changes in ventilator management and complications over time, as well as variables associated with 28-day hospital mortality in patients receiving mechanical ventilation (MV) after cardiac arrest. Methods: We performed a secondary analysis of three prospective, observational multicenter studies conducted in 1998, 2004 and 2010 in 927 ICUs from 40 countries. We screened 18,302 patients receiving MV for more than 12 hours during a one-month-period. We included 812 patients receiving MV after cardiac arrest. We collected data on demographics, daily ventilator settings, complications during ventilation and outcomes. Multivariate logistic regression analysis was performed to calculate odds ratios, determining which variables within 24 hours of hospital admission were associated with 28-day hospital mortality and occurrence of acute respiratory distress syndrome (ARDS) and pneumonia acquired during ICU stay at 48 hours after admission. Results: Among 812 patients, 100 were included from 1998, 239 from 2004 and 473 from 2010. Ventilatory management changed over time, with decreased tidal volumes (V T ) (1998: mean 8.9 (standard deviation (SD) 2) ml/kg actual body weight (ABW), 2010: 6.7 (SD 2) ml/kg ABW; 2004: 9 (SD 2.3) ml/kg predicted body weight (PBW), 2010: 7.95 (SD 1.7) ml/kg PBW) and increased positive end-expiratory pressure (PEEP) (1998: mean 3.5 (SD 3), 2010: 6.5 (SD 3); P <0.001). Patients included from 2010 had more sepsis, cardiovascular dysfunction and neurological failure, but 28-day hospital mortality was similar over time (52% in 1998, 57% in 2004 and 52% in 2010). Variables independently associated with 28-day hospital mortality were: older age, PaO 2 <60 mmHg, cardiovascular dysfunction and less use of sedative agents. Higher V T , and plateau pressure with lower PEEP were associated with occurrence of ARDS and pneumonia acquired during ICU stay. Conclusions: Protective mechanical ventilation with lower V T and higher PEEP is more commonly used after cardiac arrest. The incidence of pulmonary complications decreased, while other non-respiratory organ failures increased with time. The application of protective mechanical ventilation and the prevention of single and multiple organ failure may be considered to improve outcome in patients after cardiac arrest