A wide-orbit giant planet in the high-mass b Centauri binary system.

Planet formation occurs around a wide range of stellar masses and stellar system architectures1. An improved understanding of the formation process can be achieved by studying it across the full parameter space, particularly towards the extremes. Earlier studies of planets in close-in orbits around high-mass stars have revealed an increase in giant planet frequency with increasing stellar mass2 until a turnover point at 1.9 solar masses (M⊙), above which the frequency rapidly decreases3. This could potentially imply that planet formation is impeded around more massive stars, and that giant planets around stars exceeding 3 M⊙ may be rare or non-existent. However, the methods used to detect planets in small orbits are insensitive to planets in wide orbits. Here we demonstrate the existence of a planet at 560 times the Sun-Earth distance from the 6- to 10-M⊙ binary b Centauri through direct imaging. The planet-to-star mass ratio of 0.10-0.17% is similar to the Jupiter-Sun ratio, but the separation of the detected planet is about 100 times wider than that of Jupiter. Our results show that planets can reside in much more massive stellar systems than what would be expected from extrapolation of previous results. The planet is unlikely to have formed in situ through the conventional core accretion mechanism4, but might have formed elsewhere and arrived to its present location through dynamical interactions, or might have formed via gravitational instability.

Fast-moving features in the debris disk around AU Microscopii.

In the 1980s, excess infrared emission was discovered around main-sequence stars; subsequent direct-imaging observations revealed orbiting disks of cold dust to be the source. These 'debris disks' were thought to be by-products of planet formation because they often exhibited morphological and brightness asymmetries that may result from gravitational perturbation by planets. This was proved to be true for the ß Pictoris system, in which the known planet generates an observable warp in the disk. The nearby, young, unusually active late-type star AU Microscopii hosts a well-studied edge-on debris disk; earlier observations in the visible and near-infrared found asymmetric localized structures in the form of intensity variations along the midplane of the disk beyond a distance of 20 astronomical units. Here we report high-contrast imaging that reveals a series of five large-scale features in the southeast side of the disk, at projected separations of 10-60 astronomical units, persisting over intervals of 1-4 years. All these features appear to move away from the star at projected speeds of 4-10 kilometres per second, suggesting highly eccentric or unbound trajectories if they are associated with physical entities. The origin, localization, morphology and rapid evolution of these features are difficult to reconcile with current theories.

Instrumentation for the detection and characterization of exoplanets.

In no other field of astrophysics has the impact of new instrumentation been as substantial as in the domain of exoplanets. Before 1995 our knowledge of exoplanets was mainly based on philosophical and theoretical considerations. The years that followed have been marked, instead, by surprising discoveries made possible by high-precision instruments. Over the past decade, the availability of new techniques has moved the focus of research from the detection to the characterization of exoplanets. Next-generation facilities will produce even more complementary data that will lead to a comprehensive view of exoplanet characteristics and, by comparison with theoretical models, to a better understanding of planet formation.

Current state of transfusion in traumatic brain injury and associated coagulopathy.

Traumatic brain injury (TBI)-induced coagulopathy has long been recognized as a significant risk for poor outcomes in patients with TBI, but its pathogenesis remains poorly understood. As a result, current treatment options for the condition are limited and ineffective. The lack of information is most significant for the impact of blood transfusions on patients with isolated TBI and in the absence of confounding influences from trauma to the body and limbs and the resultant hemorrhagic shock. Here we discuss recent progress in understanding the pathogenesis of TBI-induced coagulopathy and the current state of blood transfusions for patients with TBI and associated coagulopathy.

Re-examining decompressive craniectomy medial margin distance from midline as a metric for calculating the risk of post-traumatic hydrocephalus.

Decompressive craniectomy (DC) is a life-saving procedure in severe traumatic brain injury, but is associated with higher rates of post-traumatic hydrocephalus (PTH). The relationship between the medial craniectomy margin's proximity to midline and frequency of developing PTH is controversial. The primary study objective was to determine whether average medial craniectomy margin distance from midline was closer to midline in patients who developed PTH after DC for severe TBI compared to patients that did not. The secondary objective was to determine if a threshold distance from midline could be identified, at which the risk of developing PTH increased if the DC was performed closer to midline than this threshold. A retrospective review was performed of 380 patients undergoing DC at a single institution between March 2004 and November 2014. Clinical, operative and demographic variables were collected, including age, sex, DC parameters and occurrence of PTH. Statistical analysis compared mean axial craniectomy margin distance from midline in patients with versus without PTH. Distances from midline were tested as potential thresholds. No significant difference was identified in mean axial craniectomy margin distance from midline in patients developing PTH compared with patients with no PTH (n = 24, 12.8 mm versus n = 356, 16.6 mm respectively, p = 0.086). No significant cutoff distance from midline was identified (n = 212, p = 0.201). This study, the largest to date, was unable to identify a threshold with sufficient discrimination to support clinical recommendations in terms of DC margins with regard to midline, including thresholds reportedly significant in previously published research.

Improved high-throughput ultrafiltration process enables cRNA purification for gene expression profiling.

Ultrafiltration of nucleic acids has been used for a wide variety of applications, including sequence reaction purification and amplicon cleanup prior to spotting onto microarrays. Here we describe a novel process, using ultrafiltration, that purifies cRNA products for sensitive downstream applications. Initial attempts at this high-throughput purification for cRNA resulted in low sensitivity when compared against an industry standard (silica-based bind, wash, and elute purification). We modified the ultrafiltration process to include a proteinase K preincubation and a phosphate buffer wash that, when combined, increased sensitivity and signal-to-noise ratio in microarray applications. The protocol that we have developed eliminates the use of chaotropic salts (such as guanidinium thiocyanate) that are typically used in silica binding purification methods. The data demonstrate good performance for sensitive RNA applications using well-defined metrics, and thus the technique might be useful for a broader range of nucleic acid purifications.

Identification of genes over-expressed in small cell lung carcinoma using suppression subtractive hybridization and cDNA microarray expression analysis.

To identify genes that are differentially over-expressed in Small Cell Lung Carcinoma (SCLC) we have used a combination of suppression subtractive hybridization and cDNA microarray to analyse the expression profiles of 2400 cDNAs clones. Genes that are over-expressed in SCLC were identified using 32 pairs of fluorescence-labeled cDNA samples representing various lung tumors and normal tissues. This comprehensive approach has resulted in the identification of 209 genes that are differentially over-expressed in SCLC. Quantitative real-time PCR was used to further validate the expression of 43 genes in SCLC tumors and various normal tissues. Discussed in this report are nine genes, which showed the most promising SCLC tumor to normal tissue differential expression profiles, including seven known and two novel genes. The large number of differentially expressed genes identified from this analysis and the characterization of these genes will provide valuable information in better understanding the biology of SCLC and help us in developing these gene products as potential targets for diagnostic as well as therapeutic usage.

Optimization of oligonucleotide arrays and RNA amplification protocols for analysis of transcript structure and alternative splicing.

Microarrays offer a high-resolution means for monitoring pre-mRNA splicing on a genomic scale. We have developed a novel, unbiased amplification protocol that permits labeling of entire transcripts. Also, hybridization conditions, probe characteristics, and analysis algorithms were optimized for detection of exons, exon-intron edges, and exon junctions. These optimized protocols can be used to detect small variations and isoform mixtures, map the tissue specificity of known human alternative isoforms, and provide a robust, scalable platform for high-throughput discovery of alternative splicing.

Effects of atmospheric ozone on microarray data quality.

A data anomaly was observed that affected the uniformity and reproducibility of fluorescent signal across DNA microarrays. Results from experimental sets designed to identify potential causes (from microarray production to array scanning) indicated that the anomaly was linked to a batch process; further work allowed us to localize the effect to the posthybridization array stringency washes. Ozone levels were monitored and highly correlated with the batch effect. Controlled exposures of microarrays to ozone confirmed this factor as the root cause, and we present data that show susceptibility of a class of cyanine dyes (e.g., Cy5, Alexa 647) to ozone levels as low as 5-10 ppb for periods as short as 10-30 s. Other cyanine dyes (e.g., Cy3, Alexa 555) were not significantly affected until higher ozone levels (> 100 ppb). To address this environmental effect, laboratory ozone levels should be kept below 2 ppb (e.g., with filters in HVAC) to achieve high quality microarray data.