Moving bar of light evokes vectorial spatial selectivity in the immobile rat hippocampus.

Visual cortical neurons encode the position and motion direction of specific stimuli retrospectively, without any locomotion or task demand1. The hippocampus, which is a part of the visual system, is hypothesized to require self-motion or a cognitive task to generate allocentric spatial selectivity that is scalar, abstract2,3 and prospective4-7. Here we measured rodent hippocampal selectivity to a moving bar of light in a body-fixed rat to bridge these seeming disparities. About 70% of dorsal CA1 neurons showed stable activity modulation as a function of the angular position of the bar, independent of behaviour and rewards. One-third of tuned cells also encoded the direction of revolution. In other experiments, neurons encoded the distance of the bar, with preference for approaching motion. Collectively, these demonstrate visually evoked vectorial selectivity (VEVS). Unlike place cells, VEVS was retrospective. Changes in the visual stimulus or its predictability did not cause remapping but only caused gradual changes. Most VEVS-tuned neurons behaved like place cells during spatial exploration and the two selectivities were correlated. Thus, VEVS could form the basic building block of hippocampal activity. When combined with self-motion, reward or multisensory stimuli8, it can generate the complexity of prospective representations including allocentric space9, time10,11 and episodes12.

Assessing genomic and ecological differentiation among subspecies of the rough-footed mud turtle, Kinosternon hirtipes.

Combining genetic and ecological measures of differentiation can provide compelling evidence for ecological and genetic divergence among lineages. The rough-footed mud turtle, Kinosternon hirtipes, is distributed from the Trans-Pecos region of Texas to the highlands of Central Mexico and contains 6 described subspecies, 5 of which are extant. We use ddRAD sequencing and species distribution models to assess levels of ecological and genetic differentiation among these subspecies. We also predict changes in climatically suitable habitat under different climate change scenarios and assess levels of genetic diversity and inbreeding within each lineage. Our results show that there is strong genetic and ecological differentiation among multiple lineages within K. hirtipes, and that this differentiation appears to be the result of vicariance associated with the Trans-Mexican Volcanic Belt. We propose changes to subspecies designations to more accurately reflect the evolutionary relationships among populations and assess threats to each subspecies.

Disturbance reinforces community assembly processes differentially across spatial scales.

BACKGROUND AND AIMS: There is a paucity of empirical research and a lack of predictive models concerning the interplay between spatial scale and disturbance as they affect the structure and assembly of plant communities. We proposed and tested a trait dispersion-based conceptual model hypothesizing that disturbance reinforces assembly processes differentially across spatial scales. Disturbance would reinforce functional divergence at the small scale (neighbourhood), would not affect functional dispersion at the intermediate scale (patch) and would reinforce functional convergence at the large scale (site). We also evaluated functional and species richness of native and exotic plants to infer underlying processes. Native and exotic species richness were expected to increase and decrease with disturbance, respectively, at the neighbourhood scale, and to show similar associations with disturbance at the patch (concave) and site (negative) scales. METHODS: In an arid shrubland, we estimated species richness and functional dispersion and richness within 1 m2 quadrats (neighbourhood) nested within 100 m2 plots (patch) along a small-scale natural disturbance gradient caused by an endemic fossorial rodent. Data for the site scale (2500 m2 plots) were taken from a previous study. We also tested the conceptual model through a quantitative literature review and a meta-analysis. KEY RESULTS: As spatial scale increased, disturbance sequentially promoted functional divergence, random trait dispersion and functional convergence. Functional richness was unaffected by disturbance across spatial scales. Disturbance favoured natives over exotics at the neighbourhood scale, while both decreased under high disturbance at the patch and site scales. CONCLUSIONS: The results supported the hypothesis that disturbance reinforces assembly processes differentially across scales and hampers plant invasion. The quantitative literature review and the meta-analysis supported most of the model predictions.

Transcatheter stent implantation in a child with severe stenosis of the inferior caval vein secondary to injury.

Stenosis of the Inferior Caval Vein is rarely encountered in the paediatric setting. A 5-year-old male sustained severe injuries secondary to a fall from a three story balcony and was subsequently found to have severe stenosis of the inferior caval vein resulting in extensive lymphatic drainage with chylothorax, chyloperitoneum, and severe abdominal ascites. This was successfully treated with transcatheter stent placement resulting in complete resolution of the stenosis and significant clinical improvement allowing for transfer to a rehabilitation centre and eventual discharge home.

Stenting of the ascending aorta revisited.

Despite few institutions stenting the ascending aorta, it has been discouraged because of the proximity of the aortic valve, the coronary artery orifices, and the aortic arch branches. We describe a small case series of patients having acquired stenosis of the ascending that was relieved successfully by stenting. © 2017 Wiley Periodicals, Inc.

Disturbance by an endemic rodent in an arid shrubland is a habitat filter: effects on plant invasion and taxonomical, functional and phylogenetic community structure.

Background and Aims: Disturbance often drives plant invasion and may modify community assembly. However, little is known about how these modifications of community patterns occur in terms of taxonomic, functional and phylogenetic structure. This study evaluated in an arid shrubland the influence of disturbance by an endemic rodent on community functional divergence and phylogenetic structure as well as on plant invasion. It was expected that disturbance would operate as a habitat filter favouring exotic species with short life cycles. Methods: Sixteen plots were sampled along a disturbance gradient caused by the endemic fossorial rodent Spalacopus cyanus , measuring community parameters and estimating functional divergence for life history traits (functional dispersion index) and the relative contribution to functional divergence of exotic and native species. The phylogenetic signal (Pagel's lambda) and phylogenetic community structure (mean phylogenetic distance and mean nearest taxon phylogenetic distance) were also estimated. The use of a continuous approach to the disturbance gradient allowed the identification of non-linear relationships between disturbance and community parameters. Key Results: The relationship between disturbance and both species richness and abundance was positive for exotic species and negative for native species. Disturbance modified community composition, and exotic species were associated with more disturbed sites. Disturbance increased trait convergence, which resulted in phylogenetic clustering because traits showed a significant phylogenetic signal. The relative contribution of exotic species to functional divergence increased, while that of natives decreased, with disturbance. Exotic and native species were not phylogenetically distinct. Conclusions: Disturbance by rodents in this arid shrubland constitutes a habitat filter over phylogeny-dependent life history traits, leading to phylogenetic clustering, and drives invasion by favouring species with short life cycles. Results can be explained by high phenotypic and phylogenetic resemblance between exotic and native species. The use of continuous gradients when studying the effects of disturbance on community assembly is advocated.

Quantitative echocardiographic measures in the assessment of single ventricle function post-Fontan: Incorporation into routine clinical practice.

BACKGROUND: Quantitative echocardiographic measurements of single ventricular (SV) function have not been incorporated into routine clinical practice. METHODS: A clinical protocol, which included quantitative measurements of SV deformation (global circumferential and longitudinal strain and strain rate), standard deviation of time to peak systolic strain, myocardial performance index (MPI), dP/dT from an atrioventricular valve regurgitant jet, and superior mesenteric artery resistance index, was instituted for all patients with a history of Fontan procedure undergoing echocardiography. All measures were performed real time during clinically indicated studies and were included in clinical reports. RESULTS: A total of 100 consecutive patients (mean age = 11.95±6.8 years, range 17 months-31.3 years) completed the protocol between September 1, 2014 to April 29, 2015. Deformation measures were completed in 100% of the studies, MPI in 93%, dP/dT in 55%, and superior mesenteric artery Doppler in 82%. The studies were reviewed to assess for efficiency in completing the protocol. The average time for image acquisition was 27.4±8.8 (range 10-62 minutes). The average time to perform deformation measures was 10.8±5.5 minutes (range 5-35 minutes) and time from beginning of imaging to report completion was 53.4±13.7 minutes (range 27-107 minutes). There was excellent inter-observer reliability when deformation indices were blindly repeated. Patients with a single left ventricle had significantly higher circumferential strain and strain rate, longitudinal strain and strain rate, and dP/dT compared to a single right ventricle. There were no differences in quantitative indices of ventricular function between patients <10 vs. >10 years post-Fontan. CONCLUSION: Advanced quantitative assessment of SV function post-Fontan can be consistently and efficiently performed real time during clinically indicated echocardiograms with excellent reliability.

Melody® pulmonary valve implantation in two teenage patients with congenitally corrected transposition of the great arteries status after Senning atrial switch operation.

The Melody® transcatheter pulmonary valve system was developed for placement within right ventricle-to-pulmonary artery conduits in patients with CHD for treatment of stenosis or regurgitation, providing an alternative to open-heart surgery. Abnormal systemic venous connections altering the catheter course to the right ventricle-to-pulmonary artery conduit may present a challenge to Melody® valve implantation. We present two such cases, in which the Melody® valve was successfully implanted in teenage patients with congenitally corrected transposition of the great arteries after Senning atrial switch operation. Despite the abnormal catheter course, the right ventricle-to-pulmonary artery was approachable via the right femoral vein allowing for deployment of the Melody® valve in the appropriate position. This suggests that systemic vein-to-left atrium baffles are not prohibitive of Melody® valve implantation. This is an important implication considering the substantial population of ageing patients with CHD who have undergone atrial switch. Melody® valve implantation can be considered as a viable option for treatment of these patients if they develop right ventricle-to-pulmonary artery conduit failure.

Dual-Axis Rotational Angiography is Safe and Feasible to Detect Coronary Allograft Vasculopathy in Pediatric Heart Transplant Patients: A Single-Center Experience.

Coronary allograft vasculopathy (CAV) is the leading cause of graft failure in pediatric heart transplant recipients, also adding to mortality in this patient population. Coronary angiography is routinely performed to screen for CAV, with conventional single-plane or bi-plane angiography being utilized. Dual-axis rotational coronary angiography (RA) has been described, mostly in the adult population, and may offer reduction in radiation dose and contrast volume. Experience with this in the pediatric population is limited. This study describes a single-institution experience with RA for screening for CAV in pediatric patients. The catheterization database at our institution was used to identify pediatric heart transplant recipients having undergone RA to screen for CAV. Procedural data including radiation dose, fluoroscopy time, contrast volume, and procedure time were collected for each catheterization. The number of instances in which RA was not successful, ECG changes were present, and CAV was detected were also collected for each catheterization. A total of 97 patients underwent 345 catheterizations utilizing RA. Median radiation dose-area product per kilogram was found to be 341.7 (mGy cm(2)/kg), total air kerma was 126.8 (mGy), procedure time was 69 min, fluoroscopy time was 9.9 min, and contrast volume was 13 ml. A total of 17 (2 %) coronary artery injections out of 690 could not be successfully imaged using RA. A total of 14 patients had CAV noted at any point, 10 of whom had progressive CAV. Electrocardiographic changes were documented in a total of 10 (3 %) RA catheterizations. Procedural characteristics did not differ between serial catheterizations. RA is safe and feasible for CAV screening in pediatric heart transplant recipients while offering coronary imaging in multiple planes compared to conventional angiography.

Obstructive jaundice caused by a pancreaticoduodenal pseudoaneurysm.

Obstructive jaundice caused by a pancreaticoduodenal pseudoaneurysm, probably related to a chronic pancreatitis.

A rare presentation of gallstones: Bouveret´s syndrome, a case report.

CT images and endoscopic findings in a case of Bouveret's syndrome.

Home range of three turtle species in Central Yucatan. A comparative study.

Home range is a fundamental characteristic of an animal natural history. The study of home range provides information on the sites where organisms forage for food, find shelter, or locate mates. Home range size and shape can change throughout the lifespan of an organism, during the year, or across seasons, driven by resource availability and the basic needs for each organism. For freshwater and semi-aquatic turtles, home range is greatly affected by water availability, humidity, and temperature throughout the year, nevertheless demographic factors such age and sex are also important determinants of home range size. In this study we estimated home range and dispersal movements for Kinosternon creaseri, Terrapene yucatana, and Rhinoclemmys areolata in a semi-tropical dry forest in central Yucatán. For a two-year period, turtles were surveyed using hoop traps and visual encounters. Twenty-one individuals (5-8 per species) were equipped with radio transmitters to track them across the landscape. Distances between relocations and home range were compared across species seasons, sex, and interactions of these variables. Monthly average movements were positively correlated with rain in the three species studied. Home range of R. areolata was larger than those of K. creaseri and T. yucatana. Home range of the three studied species were larger during the wet season. Home range overlap index within same species individuals was higher during the rainy than dry season, but overall overlap is low between and within species.

Successful staged surgical repair using rapid pulmonary artery banding in a very-low-birth-weight premature infant who had d-transposition of the great arteries with an intact ventricular septum.

The arterial switch operation is the surgical correction of choice for patients born with d-transposition of the great arteries (d-TGA) and an intact ventricular septum. However, prematurity and very low birth weight present both technical and physiologic challenges to this approach. Furthermore, in the setting of d-TGA and an intact ventricular septum, delaying intervention results in deconditioning of the left ventricle, rendering the patient a poor candidate for the arterial switch operation. The report presents an infant born at 27 weeks gestation weighing 1.01 kg who as a newborn underwent a successful urgent balloon atrial septostomy, pulmonary artery banding, and a central shunt on day of life (DOL) 82 and the arterial switch operation on DOL 93.

Evidence for the morphological constraint hypothesis and optimal offspring size theory in the Mexican mud turtle (Kinosternon integrum).

Optimal offspring size theory states that natural selection should balance reproductive output by optimizing between offspring size and offspring number. If a species has evolved an optimal offspring size, the fitness of larger females should be increased by simply producing more offspring of an optimum size. In contrast, when offspring size is not optimized, the morphological constraint hypothesis may apply, and in this case, maternal fitness is increased by producing the greatest number of the largest offspring that mothers are physically capable of producing. We used a log-log allometric regression approach on clutch size, egg size, and body size data to test the application of optimal offspring size theory and the morphological constraint hypothesis in the Mexican mud turtle (Kinosternon integrum) in southern Mexico. Our results indicate that this turtle seems to follow the morphological constraint hypothesis when all data are analyzed together, but when data are divided between small (< 140 mm plastron length) and large females (> 140 mm plastron length), optimal offspring (egg) size theory was supported only in large females, while the morphological constraint hypothesis was supported in small females. Our results thus indicate that K. integrum females may increase their fitness in two different, size-dependent ways as they grow from size at sexual maturity to maximum body size.

Evolutionary transitions in diet influence the exceptional diversification of a lizard adaptive radiation.

BACKGROUND: Diet is a key component of a species ecological niche and plays critical roles in guiding the trajectories of evolutionary change. Previous studies suggest that dietary evolution can influence the rates and patterns of species diversification, with omnivorous (animal and plant, 'generalist') diets slowing down diversification compared to more restricted ('specialist') herbivorous and carnivorous diets. This hypothesis, here termed the "dietary macroevolutionary sink" hypothesis (DMS), predicts that transitions to omnivorous diets occur at higher rates than into any specialist diet, and omnivores are expected to have the lowest diversification rates, causing an evolutionary sink into a single type of diet. However, evidence for the DMS hypothesis remains conflicting. Here, we present the first test of the DMS hypothesis in a lineage of ectothermic tetrapods-the prolific Liolaemidae lizard radiation from South America. RESULTS: Ancestral reconstructions suggest that the stem ancestor was probably insectivorous. The best supported trait model is a diet-dependent speciation rate, with independent extinction rates. Herbivory has the highest net diversification rate, omnivory ranks second, and insectivory has the lowest. The extinction rate is the same for all three diet types and is much lower than the speciation rates. The highest transition rate was from omnivory to insectivory, and the lowest transition rates were between insectivory and herbivory. CONCLUSIONS: Our findings challenge the core prediction of the DMS hypothesis that generalist diets represent an 'evolutionary sink'. Interestingly, liolaemid lizards have rapidly and successfully proliferated across some of the world's coldest climates (at high elevations and latitudes), where species have evolved mixed arthropod-plant (omnivore) or predominantly herbivore diets. This longstanding observation is consistent with the higher net diversification rates found in both herbivory and omnivory. Collectively, just like the evolution of viviparity has been regarded as a 'key adaptation' during the liolaemid radiation across cold climates, our findings suggest that transitions from insectivory to herbivory (bridged by omnivory) are likely to have played a role as an additional key adaptation underlying the exceptional diversification of these reptiles across extreme climates.

Context-dependent recruitment of Guettarda viburnoides in a Neotropical forest-savanna mosaic.

PREMISE OF THE STUDY: Seed dispersal is a key process for plant regeneration in tropical areas. Differences in disperser behavior result in a nonrandom distribution of seeds among habitats. Patterns of seed dispersal may cascade through the entire recruitment phase or uncoupling between developmental stages may occur such that patterns of seed dispersal are discordant with patterns of recruitment. Here, we analyzed how habitat and interannual variability affect the recruitment dynamics of a bird-dispersed tree, Guettarda viburnoides (RUB.). METHODS: Over 3 years, we determined the habitats where seeds of G. viburnoides are dispersed, and we experimentally quantified postdispersal seed predation, seedling emergence, and survival in four habitats of a forest-savanna mosaic in Bolivia. KEY RESULTS: Habitat affected seed dispersal, seed predation, and seedling emergence. The strength of postdispersal processes, however, varied between years and no consistent within-habitat pattern emerged. Uncoupling among different life-stages was observed across habitats, and spatial concordance was found between seed rain and sapling recruitment patterns. CONCLUSIONS: Habitat can affect seed dispersal, postdispersal processes and the recruitment dynamics of a Neotropical tree in a heterogeneous landscape. Additionally, our results show interannual variability in the strength of postdispersal processes, which leads to shifts in habitat suitability between years. Therefore, to better understand the role of site suitability for recruitment, we need to explicitly consider not only variation in habitat-specificity for dispersal and postdispersal processes, but also how this variation can shift under different environmental conditions-that is, the context dependence of suitability.

Modification of Transfer RNA Levels Affects Cyclin Aggregation and the Correct Duplication of Yeast Cells.

Codon usage bias (the preferential use of certain synonymous codons (optimal) over others is found at the organism level (intergenomic) within specific genomes (intragenomic) and even in certain genes. Whether it is the result of genetic drift due to GC/AT content and/or natural selection is a topic of intense debate. Preferential codons are mostly found in genes encoding highly-expressed proteins, while lowly-expressed proteins usually contain a high proportion of rare (lowly-represented) codons. While optimal codons are decoded by highly expressed tRNAs, rare codons are usually decoded by lowly-represented tRNAs. Whether rare codons play a role in controlling the expression of lowly- or temporarily-expressed proteins is an open question. In this work we approached this question using two strategies, either by replacing rare glycine codons with optimal counterparts in the gene that encodes the cell cycle protein Cdc13, or by overexpression the tRNA Gly that decodes rare codons from the fission yeast, Schizosaccharomyces pombe. While the replacement of synonymous codons severely affected cell growth, increasing tRNA levels affected the aggregation status of Cdc13 and cell division. These lead us to think that rare codons in lowly-expressed cyclin proteins are crucial for cell division, and that the overexpression of tRNA that decodes rare codons affects the expression of proteins containing these rare codons. These codons may be the result of the natural selection of codons in genes that encode lowly-expressed proteins.

Pulmonary artery interventions after the arterial switch operation: Unique and significant risks.

BACKGROUND: In the modern era, results of the arterial switch operation (ASO) for transposition of the great arteries are excellent. However, because of the LeCompte maneuver, there may be a propensity for development of pulmonary artery stenosis. We encountered atypical complications of pulmonary artery stenting in patients after the ASO, including aorto-pulmonary fistula and coronary compression. METHODS: We performed a 10-year retrospective review of catheterizations performed in patients after ASO in our institution with a focus on adverse events. RESULTS: Diagnostic and interventional catheterizations were performed in 47 patients. In 29 patients, 37 interventional procedures performed, which included pulmonary artery angioplasty and/or stenting. In this group, there were five major adverse events (14%), including three aorto-pulmonary fistulae and one coronary artery compression among patients having stent implantation or stent redilation. In addition, there were 6/37 (16%) intended stent procedures, which were aborted because there appeared to be high-risk of significant adverse events. CONCLUSIONS: This review suggests that percutaneous intervention on pulmonary artery stenosis after ASO has high-risk and should be undertaken advisedly. Prior thorough evaluation of coronary arteries is mandatory as coronary reimplantation sites may be adjacent to sites of pulmonary artery stenosis. Furthermore, if pulmonary artery stent implantation or stent redilation is contemplated, the risk of stent fracture and possible AP fistula should be recognized. Primary use of reinforced covered stents should be considered.

Endogenous and Foreign Nucleoid-Associated Proteins of Bacteria: Occurrence, Interactions and Effects on Mobile Genetic Elements and Host's Biology.

Mobile Genetic Elements (MGEs) are mosaics of functional gene modules of diverse evolutionary origin and are generally divergent from the hosts´ genetic background. Existing biases in base composition and codon usage of these elements` genes impose transcription and translation limitations that may affect the physical and regulatory integration of MGEs in new hosts. Stable appropriation of the foreign DNA depends on a number of host factors among which are the Nucleoid-Associated Proteins (NAPs). These small, basic, highly abundant proteins bind and bend DNA, altering its topology and folding, thereby affecting all known essential DNA metabolism related processes. Both chromosomally- (endogenous) and MGE- (foreign) encoded NAPs have been shown to exist in bacteria. While the role of host-encoded NAPs in xenogeneic silencing of both episomal (plasmids) and integrative MGEs (pathogenicity islands and prophages) is well acknowledged, less is known about the role of MGE-encoded NAPs in the foreign elements biology or their influence on the host's chromosome expression dynamics. Here we review existing literature on the topic, present examples on the positive and negative effects that endogenous and foreign NAPs exert on global transcriptional gene expression, MGE integrative and excisive recombination dynamics, persistence and transfer to suitable hosts and discuss the nature and relevance of synergistic and antagonizing higher order interactions between diverse types of NAPs.