Correlated decay of triplet excitations in the Shastry-Sutherland compound SrCu2_2(BO3_3)2_2

The temperature dependence of the gapped triplet excitations (triplons) in the 2D Shastry-Sutherland quantum magnet SrCu$_2$(BO$_3$)$_2$ is studied by means of inelastic neutron scattering. The excitation amplitude rapidly decreases as a function of temperature while the integrated spectral weight can be explained by an isolated dimer model up to 10~K. Analyzing this anomalous spectral line-shape in terms of damped harmonic oscillators shows that the observed damping is due to a two-component process: one component remains sharp and resolution limited while the second broadens. We explain the underlying mechanism through a simple yet quantitatively accurate model of correlated decay of triplons: an excited triplon is long-lived if no thermally populated triplons are near-by but decays quickly if there are. The phenomenon is a direct consequence of frustration induced triplon localization in the Shastry--Sutherland lattice.Comment: 5 pages, 4 figure

Health care disparities in colorectal and esophageal cancer

Background: We aimed to identify differences in disparities among patients with a cancer in which screening is widely recommended (colorectal cancer [CRC]) and one in which it is not (esophageal cancer). Methods: A retrospective analysis was performed using 2004–2015 data from the National Cancer Database. Multivariable generalized logistic regression was used to identify potential differences in the effect of disparities in stage at diagnosis. Results: A total of 96,524 esophageal cancer patients and 361,187 CRC patients were included. Black patients, longer travel distances, and lower educational attainment were only associated with increased odds of stage IV CRC. While both Medicaid and uninsured patients were more likely to be diagnosed with stage IV esophageal and CRC, the effect was larger among CRC patients. From 2004 to 2015, the rates of stage IV esophageal cancer decreased from 42.0% to 38.2%, while the rates of stage IV CRC increased from 36.9% to 40.8% (p < 0.0001). Conclusions: Disparities are more pronounced in CRC, compared to esophageal cancer. Equity in access to screening and cancer care should be prioritized

Cholecystectomy Vs. Cholecystostomy for the Management of Acute Cholecystitis in Elderly Patients

Background: Data comparing outcomes following cholecystectomy and cholecystostomy tube placement (CTP) in elderly patients are lacking. We aimed to compare the post-procedural outcomes between cholecystectomy and CTP in elderly patients with acute cholecystitis. Methods: We performed a retrospective, population-based analysis using the National Inpatient Sample for the period 2000–2014. Patients ≥ 65 years old admitted with a primary diagnosis of acute cholecystitis and who underwent either cholecystectomy or CTP during their hospitalization were included. Multivariable linear and logistic regression models were used to analyze post-procedural complications, mortality, length of stay, and total charges. The effect of procedure type on patient outcomes, stratified by acalculous and calculous cholecystitis, was also performed. Results: A total of 200,915 patients were included, of which 7516 underwent CTP and 193,399 underwent cholecystectomy. The median age of patients undergoing CTP and cholecystectomy was 80 (IQR 73–87) and 75 (IQR 70–81), respectively. Patients undergoing CTP were more likely to have post-procedural infection (OR 2.25; 95% CI 2.07, 2.45), bleeding (OR 1.28; 95% CI 1.19, 1.37), and inpatient mortality (OR 9.27; 95% CI 7.95, 10.81). On average, CTP patients stayed 1.25 days longer (95% CI 1.14, 1.37) in hospital after the procedure. The benefits of cholecystectomy were consistent in patients with acalculous and calculous cholecystitis. Conclusions: Elderly patients with both acalculous and calculous acute cholecystitis managed with CTP have higher incidences of post-procedural morbidity and mortality, and longer post-procedure length of hospital stay, as compared to cholecystectomy. Unless prohibitive surgical risks exist, elderly patients with acute cholecystitis should undergo cholecystectomy

Anatomic Location and Mechanism of Injury Correlating with Prehospital Deaths in Sub-Saharan Africa

Introduction: Trauma is a large contributor to morbidity and mortality in developing countries. We sought to determine which anatomic injury locations and mechanisms of injury predispose to prehospital mortality in Malawi to help target preventive and therapeutic interventions. We hypothesized that head injury would result in the highest prehospital mortality. Methods: This was a retrospective analysis of all trauma patients presenting to Kamuzu Central Hospital in Lilongwe, Malawi, from 2008 to 2015. Independent variables included baseline characteristics, anatomic location of primary injury, mechanism of injury, and severity of secondary injuries. Multivariable logistic regression was used to assess the effect of primary injury location and injury mechanism on prehospital death, after adjusting for confounders. Effect measure modification of the primary injury site/prehospital death relationship by injury mechanism (stratified into intentional and unintentional injury) was assessed. Results: Of 85,806 patients, 701 died in transit (0.8%). Five hundred and five (72%) of these patients sustained a primary head injury. After adjustment, head injury was the anatomic location most associated with prehospital death (OR 11.81 (95% CI 6.96–20.06, p < 0.0001). The mechanisms of injury most associated with prehospital death were gunshot wounds (OR 38.23, 95% CI 17.66–87.78, p < 0.0001) and pedestrian hit by vehicle (OR 2.62, 95% CI 1.92–3.55, p < 0.0001). Among head injury patients, the odds of prehospital mortality were higher with unintentional injuries. Conclusions: Head injuries are the most common causes of prehospital death in Malawi, while pedestrians hit by vehicles are the most common mechanisms. In a resource-poor setting, preventive measures are critical in averting mortality

Spin density wave induced disordering of the vortex lattice in superconducting La2−x_{2-x}Srx_xCuO4_4

We use small angle neutron scattering to study the superconducting vortex lattice in La$_{2-x}$Sr$_x$CuO$_4$ as a function of doping and magnetic field. We show that near optimally doping the vortex lattice coordination and the superconducting coherence length $\xi$ are controlled by a van-Hove singularity crossing the Fermi level near the Brillouin zone boundary. The vortex lattice properties change dramatically as a spin-density-wave instability is approached upon underdoping. The Bragg glass paradigm provides a good description of this regime and suggests that SDW order acts as a novel source of disorder on the vortex lattice.Comment: Accepted in Phys. Rev.

The Disk and Extraplanar Environment of NGC 247

The stellar content of the spiral galaxy NGC 247 is investigated. The main sequence turn-off (MSTO) in the inner 12 kpc of the disk corresponds to an age of 6 Myr. A mean star formation rate (SFR) of 0.1 solar masses per year during the past 16 Myr is computed from star counts. The color of the red supergiant plume does not change with radius, suggesting that the mean metallicity of young stars does not vary by more than 0.1 dex. The number of bright main sequence stars per local stellar mass density climbs towards larger radii out to a distance of 12 kpc; the scale lengths that characterize the radial distributions of young and old stars in the disk thus differ. The density of bright main sequence stars with respect to projected HI mass gradually drops with increasing radius. The population of very young stars disappears in the outer disk; the MSTO at galactocentric radii between 12 and 15 kpc corresponds to 16 Myr, while between 15 and 18 kpc the age is > 40 Myr. Red giant branch (RGB) stars are resolved at a projected minor axis galactocentric distance of 12 kpc. There is a broad spread in metallicity among the RGB stars, with a mean [M/H] = -1.2. The RGB-tip occurs at i' = 24.5 +/- 0.1, indicating that the distance modulus is 27.9 +/- 0.1. Luminous AGB stars with an age 3 Gyr are also seen in this field.Comment: Includes 16 eps figures; to appear in the Astrophysical Journa

Thoracic Enhanced Recovery After Surgery: Single Academic Center Observations After Implementation

Background: Enhanced recovery after surgery (ERAS) is an evidence-based, multidisciplinary perioperative care model shown to reduce complications and hospital length of stay (LOS). While some thoracic ERAS studies were inconclusive, others demonstrated that ERAS improves patient outcomes after lung resections and provides more cost-effective care. We aimed to investigate the effects of preliminary implementation of an ERAS protocol, in comparison with conventional care, on lung resection outcomes at a single academic institution. Methods: In this observational study, adult patients undergoing lung resections during the pre-ERAS (April 2014 to September 2015) and post-ERAS (January 2016 to May 2017) periods were identified. Relevant demographic, preoperative, anesthesia, and surgical variables were collected. Pre-ERAS and post-ERAS cohorts were compared in terms of hospital LOS, postoperative complications, and 30-day outcomes. Results: We identified 264 patients, half in each cohort. Pre-ERAS and post-ERAS groups were similar with respect to age, race, and comorbidities. There were no significant differences in LOS, complications, 30-day readmission and mortality rates, or patient-reported outcomes. Of the patients with prolonged LOS, 31% had pulmonary complications, almost half of which were prolonged air leaks. ERAS adherence rate was approximately 60%. Conclusions: In the first year of implementation, median LOS, complications, and 30-day outcomes did not differ significantly between the pre-ERAS and post-ERAS groups. Prolonged air leaks commonly led to prolonged LOS; therefore, thoracic ERAS protocols could include interventions to reduce air leak and consideration for discharging patients with chest tubes placed to Heimlich valves. Buy-in and adherence to a new protocol are necessary for implementation to be effective

Evaluation of different decellularization protocols on the generation of pancreas-derived hydrogels

Different approaches have investigated the effects of different extracellular matrices (ECMs) and three-dimensional (3D) culture on islet function, showing encouraging results. Ideally, the proper scaffold should mimic the biochemical composition of the native tissue as it drives numerous signaling pathways involved in tissue homeostasis and functionality. Tissue-derived decellularized biomaterials can preserve the ECM composition of the native tissue making it an ideal scaffold for 3D tissue engineering applications. However, the decellularization process may affect the retention of specific components, and the choice of a proper detergent is fundamental in preserving the native ECM composition. In this study, we evaluated the effect of different decellularization protocols on the mechanical properties and biochemical composition of pancreatic ECM (pECM) hydrogels. Fresh porcine pancreas tissue was harvested, cut into small pieces, rinsed in water, and treated with two different detergents (sodium dodecyl sulfate [SDS] or Triton X-100) for 1 day followed by 3 days in water. Effective decellularization was confirmed by PicoGreen assay, Hoescht, and H&amp;E staining, showing no differences among groups. Use of a protease inhibitor (PI) was also evaluated. Effective decellularization was confirmed by PicoGreen assay and hematoxylin and eosin (H&amp;E) staining, showing no differences among groups. Triton-treated samples were able to form a firm hydrogel under appropriate conditions, while the use of SDS had detrimental effects on the gelation properties of the hydrogels. ECM biochemical composition was characterized both in the fresh porcine pancreas and all decellularized pECM hydrogels by quantitative mass spectrometry analysis. Fibrillar collagen was the major ECM component in all groups, with all generated hydrogels having a higher amount compared with fresh pancreas. This effect was more pronounced in the SDS-treated hydrogels when compared with the Triton groups, showing very little retention of other ECM molecules. Conversely, basement membrane and matricellular proteins were better retained when the tissue was pretreated with a PI and decellularized in Triton X-100, making the hydrogel more similar to the native tissue. In conclusion, we showed that all the protocols evaluated in the study showed effective tissue decellularization, but only when the tissue was pretreated with a PI and decellularized in Triton detergent, the biochemical composition of the hydrogel was closer to the native tissue ECM. The article compares different methodologies for the generation of a pancreas-derived hydrogel for tissue engineering applications. The biochemical characterization of the newly generated hydrogel shows that the material retains all the extracellular molecules of the native tissue and is capable of sustaining functionality of the encapsulated beta-cells

Dynamic Changes in the MicroRNA Expression Profile Reveal Multiple Regulatory Mechanisms in the Spinal Nerve Ligation Model of Neuropathic Pain

Neuropathic pain resulting from nerve lesions or dysfunction represents one of the most challenging neurological diseases to treat. A better understanding of the molecular mechanisms responsible for causing these maladaptive responses can help develop novel therapeutic strategies and biomarkers for neuropathic pain. We performed a miRNA expression profiling study of dorsal root ganglion (DRG) tissue from rats four weeks post spinal nerve ligation (SNL), a model of neuropathic pain. TaqMan low density arrays identified 63 miRNAs whose level of expression was significantly altered following SNL surgery. Of these, 59 were downregulated and the ipsilateral L4 DRG, not the injured L5 DRG, showed the most significant downregulation suggesting that miRNA changes in the uninjured afferents may underlie the development and maintenance of neuropathic pain. TargetScan was used to predict mRNA targets for these miRNAs and it was found that the transcripts with multiple predicted target sites belong to neurologically important pathways. By employing different bioinformatic approaches we identified neurite remodeling as a significantly regulated biological pathway, and some of these predictions were confirmed by siRNA knockdown for genes that regulate neurite growth in differentiated Neuro2A cells. In vitro validation for predicted target sites in the 3′-UTR of voltage-gated sodium channel Scn11a, alpha 2/delta1 subunit of voltage-dependent Ca-channel, and purinergic receptor P2rx ligand-gated ion channel 4 using luciferase reporter assays showed that identified miRNAs modulated gene expression significantly. Our results suggest the potential for miRNAs to play a direct role in neuropathic pain