The circumstellar disk of AB Aurigae: evidence for envelope accretion at late stages of star formation?

The circumstellar disk of AB Aurigae has garnered strong attention owing to the apparent existence of spirals at a relatively young stage and also the asymmetric disk traced in thermal dust emission. However, the physical conditions of the spirals are still not well understood. The origin of the asymmetric thermal emission is unclear. We observed the disk at 230 GHz (1.3 mm) in both the continuum and the spectral line ^12CO J=2-1 with IRAM 30-m, the Plateau de Bure interferometer, and the Submillimeter Array to sample all spatial scales from 0.37" to about 50". To combine the data obtained from these telescopes, several methods and calibration issues were checked and discussed. The 1.3 mm continuum (dust) emission is resolved into inner disk and outer ring. Molecular gas at high velocities traced by the CO line is detected next to the stellar location. The inclination angle of the disk is found to decrease toward the center. On a larger scale, based on the intensity weighted dispersion and the integrated intensity map of ^12CO J=2-1, four spirals are identified, where two of them are also detected in the near infrared. The total gas mass of the 4 spirals (M_spiral) is 10^-7 < M_spiral < 10^-5 M_sun, which is 3 orders of magnitude smaller than the mass of the gas ring. Surprisingly, the CO gas inside the spiral is apparently counter-rotating with respect to the CO disk, and it only exhibits small radial motion. The wide gap, the warped disk, and the asymmetric dust ring suggest that there is an undetected companion with a mass of 0.03 M_sun at a radius of 45 AU. Although an hypothetical fly-by cannot be ruled out, the most likely explanation of the AB Aurigae system may be inhomogeneous accretion well above or below the main disk plane from the remnant envelope, which can explain both the rotation and large-scale motions detected with the 30-m image.Comment: 17 pages, 13 figures, accepted for publication in A&A journal. Typos are correcte

Circumbinary Ring, Circumstellar disks and accretion in the binary system UY Aurigae

Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary disks (CB) may be in the midst of planet formation. However, there are very few CB disks detected. We revisit one of the known CB disks, the UY Aurigae system, and probe 13CO 2-1, C18O 2-1, SO 5(6)-4(5) and 12CO 3-2 line emission and the thermal dust continuum. Our new results confirm the existence of the CB disk. In addition, the circumstellar (CS) disks are clearly resolved in dust continuum at 1.4 mm. The spectral indices between the wavelengths of 0.85 mm and 6 cm are found to be surprisingly low, being 1.6 for both CS disks. The deprojected separation of the binary is 1.26" based on our 1.4 mm continuum data. This is 0.07" (10 AU) larger than in earlier studies. Combining the fact of the variation of UY Aur B in $R$ band, we propose that the CS disk of an undetected companion UY Aur Bb obscures UY Aur Ba. A very complex kinematical pattern inside the CB disk is observed due to a mixing of Keplerian rotation of the CB disk, the infall and outflow gas. The streaming gas accreting from the CB ring toward the CS disks and possible outflows are also identified and resolved. The SO emission is found to be at the bases of the streaming shocks. Our results suggest that the UY Aur system is undergoing an active accretion phase from the CB disk to the CS disks. The UY Aur B might also be a binary system, making the UY Aur a triple system.Comment: 14 pages, 11 figures; accepted for publication in Ap

Correlation of Clinical Symptoms with Temporal and Frontoparietal Lobe Response During an Auditory \u27Odball\u27 Task of Chronic and First Episode Schizophrenia Patients (N=190)

The disorder of schizophrenia is defined by the presence of positive and negative clinical symptoms. One of the hallmark positive symptoms is the presence of auditory hallucinations which have previously been studied to involve bilateral temporal lobe anamolies. Our study seeks to further define and potentially quantify these anamolies in temporal lobe response by looking at the correlation of clinical symptoms with temporal lobe activation. To accomplish this task we have subjected 22 first episode and 64 chronic patients along with 104 matched healthy controls to a functional MRI scan while undergoing an auditory oddball\u27 task. Analysis of this data is unique in the use of independent component analysis (ICA) via Matlab toolbox (GIFT). Results showed expected positive activation patterns for temporal lobe activity across all participants but revealed no statistically significant differences within patient populations (first episode (FE) vs. chronic) or between patients and matched healthy controls. We observed strong correlation coefficients for both patient groups as positive symptoms were negatively correlated to temporal lobe response (FE rho = -0.31, chronic rho = -0.20). Negative symptoms were positively correlated but only statistically significant for first episode patients (rho = +0.23). This data is consistent with other studies involving EEG recordings of P300 amplitude response. Finally, in analyzing frontoparietal (FP) lobe activation we showed statistically signficant activation differences between patients and controls. This result could potentially be used as a future diagnostic test. In addition, we uncovered another point of asymmetry in first episode patients whose right FP lobe showed a nearly two-fold correlation coefficient value versus the left FP lobe for negative symptoms. This unique asymmetry could offer a new area of focus for future researchers into the pathophysiology of schizophrenia.\u2

Role of the lectin pathway of complement in hematopoietic stem cell transplantation-associated endothelial injury and thrombotic microangiopathy.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) is a life-threatening syndrome that occurs in adult and pediatric patients after hematopoietic stem cell transplantation. Nonspecific symptoms, heterogeneity within study populations, and variability among current diagnostic criteria contribute to misdiagnosis and underdiagnosis of this syndrome. Hematopoietic stem cell transplantation and associated risk factors precipitate endothelial injury, leading to HSCT-TMA and other endothelial injury syndromes such as hepatic veno-occlusive disease/sinusoidal obstruction syndrome, idiopathic pneumonia syndrome, diffuse alveolar hemorrhage, capillary leak syndrome, and graft-versus-host disease. Endothelial injury can trigger activation of the complement system, promoting inflammation and the development of endothelial injury syndromes, ultimately leading to organ damage and failure. In particular, the lectin pathway of complement is activated by damage-associated molecular patterns (DAMPs) on the surface of injured endothelial cells. Pattern-recognition molecules such as mannose-binding lectin (MBL), collectins, and ficolins-collectively termed lectins-bind to DAMPs on injured host cells, forming activation complexes with MBL-associated serine proteases 1, 2, and 3 (MASP-1, MASP-2, and MASP-3). Activation of the lectin pathway may also trigger the coagulation cascade via MASP-2 cleavage of prothrombin to thrombin. Together, activation of complement and the coagulation cascade lead to a procoagulant state that may result in development of HSCT-TMA. Several complement inhibitors targeting various complement pathways are in clinical trials for the treatment of HSCT-TMA. In this article, we review the role of the complement system in HSCT-TMA pathogenesis, with a focus on the lectin pathway

A targeted gene panel that covers coding, non-coding and short tandem repeat regions improves the diagnosis of patients with neurodegenerative diseases

Genetic testing for neurodegenerative diseases (NDs) is highly challenging because of genetic heterogeneity and overlapping manifestations. Targeted-gene panels (TGPs), coupled with next-generation sequencing (NGS), can facilitate the profiling of a large repertoire of ND-related genes. Due to the technical limitations inherent in NGS and TGPs, short tandem repeat (STR) variations are often ignored. However, STR expansions are known to cause such NDs as Huntington\u27s disease and spinocerebellar ataxias type 3 (SCA3). Here, we studied the clinical utility of a custom-made TGP that targets 199 NDs and 311 ND-associated genes on 118 undiagnosed patients. At least one known or likely pathogenic variation was found in 54 patients; 27 patients demonstrated clinical profiles that matched the variants; and 16 patients whose original diagnosis were refined. A high concordance of variant calling were observed when comparing the results from TGP and whole-exome sequencing of four patients. Our in-house STR detection algorithm has reached a specificity of 0.88 and a sensitivity of 0.82 in our SCA3 cohort. This study also uncovered a trove of novel and recurrent variants that may enrich the repertoire of ND-related genetic markers. We propose that a combined comprehensive TGPs-bioinformatics pipeline can improve the clinical diagnosis of NDs

Blood and Marrow Transplant Clinical Trials Network Toxicity Committee Consensus Summary: Thrombotic Microangiopathy after Hematopoietic Stem Cell Transplantation

AbstractThe syndrome of microangiopathic hemolysis associated with renal failure, neurologic impairment, or both is a recognized complication of hematopoietic stem cell transplantation. This entity is often called hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP), yet it is clear that the pathophysiology of transplant-associated HUS/TTP is different from that of classic HUS or TTP. Furthermore, the incidence of this syndrome varies from 0.5% to 76% in different transplant series, primarily because of the lack of a uniform definition. The toxicity committee of the Blood and Marrow Transplant Clinical Trials Network has reviewed the current literature on transplant-related HUS/TTP and recommends that it be henceforth renamed posttransplantation thrombotic microangiopathy (TMA). An operational definition for TMA based on the presence of microangiopathic hemolysis and renal and/or neurologic dysfunction is proposed. The primary intervention after diagnosis of TMA should be withdrawal of calcineurin inhibitors. Plasma exchange, although frequently used in this condition, has not been proven to be effective. In the absence of definitive trials, plasma exchange cannot be considered a standard of care for TMA. It is hoped that these positions will improve the identification and reporting of this devastating complication after hematopoietic stem cell transplantation and facilitate future clinical studies for its prevention and treatment

A Prognostic Score for Patients with Acute Leukemia or Myelodysplastic Syndromes Undergoing Allogeneic Stem Cell Transplantation

AbstractAllogeneic hematopoietic stem cell transplantation (SCT) has the potential to cure patients with acute leukemia or myelodysplastic syndromes (MDS), but a number of prognostic factors can influence the outcome of transplantation. At present, no transplantation-specific risk score exists for this patient population. We propose a simple scoring system for patients with acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), or MDS, based on a retrospective analysis of 445 patients undergoing SCT at our institution (divided into training and validation subsets). The score depends on 5 variables: age, disease, stage at transplantation, cytogenetics, and pretransplantation ferritin. It divides patients into 3 groups of comparable size, with 5-year overall survival (OS) of 56% (low risk), 22% (intermediate risk), and 5% (high risk). This prognostic score could be useful in making treatment decisions for individual patients, in stratifying patients entering clinical trials, and in adjusting transplantation outcomes across centers under the new federal reporting rules