Synthesis of 2-Amino-2-deoxy Sugars via Boron-Catalyzed Coupling of Glycosyl Fluorides and Silyl Ether Acceptors.

Although aminosugars are important components in a variety of bioactive molecules, their stereoselective formation is made challenging by the Lewis basic nature of amino substituents. Additionally, the use of -acyl protecting groups is often problematic due to the competing formation of oxazolines during the glycosylation of 2-aminosugar derivatives. Herein, we report a boron-catalyzed strategy utilizing silyl ether glycosyl acceptors and 2-aminosugar donors that employs the 2,2,2-trichloroethoxycarbonyl (Troc) protecting group for the C2 amino functionality in glycosyl fluorides.

Oxidative Cross Dehydrogenative Coupling of -Heterocycles with Aldehydes through C()-H Functionalization.

Existing methodologies for metal-catalyzed cross-couplings typically rely on preinstallation of reactive functional groups on both reaction partners. In contrast, C-H functionalization approaches offer promise in simplification of the requisite substrates; however, challenges from low reactivity and similar reactivity of various C-H bonds introduce considerable complexity. Herein, the oxidative cross dehydrogenative coupling of α-amino C()-H bonds and aldehydes to produce ketone derivatives is described using an unusual reaction medium that incorporates the simultaneous use of di--butyl peroxide as an oxidant and zinc metal as a reductant.

Comparison of acoustic particle acceleration detection capabilities in three shark species.

Behavioural studies have shown that sharks are capable of directional orientation to sound. However, only one previous experiment addresses the physiological mechanisms of directional hearing in sharks. Here, we used a directional shaker table in combination with the auditory evoked potential (AEP) technique to understand the broadscale directional hearing capabilities in the New Zealand carpet shark (Cephaloscyllium isabellum), rig shark (Mustelus lenticulatus) and school shark (Galeorhinus galeus).

Sources of Postacute Care Episode Payment Variation After Traumatic Hip Fracture Repair Among Medicare Beneficiaries: Cross-Sectional Retrospective Study.

Unlabelled: The objective of this study was to evaluate how much variation in postacute care (PAC) spending after traumatic hip fracture exists between hospitals, and to what degree this variation is explained by patient factors, hospital factors, PAC setting, and PAC intensity.

Background: Traumatic hip fracture is a common and costly event. This is particularly relevant given our aging population and that a substantial proportion of these patients are discharged to PAC settings.

Tolerability and Efficacy of a 10:25 Preparation of Δ9-Tetrahydrocannabinol and Cannabidiol for Treatment of Chronic Back or Neck Pain: A Multiple-Dose Escalation Study.

Introduction: The aim was to demonstrate the safety and tolerability of cannabidiol (CBD) with Δ9-THC in patients with moderate to severe chronic back or neck pain unresponsive to over-the-counter non-opioid analgesics.

Methods: This was a non-randomized, single-arm, open-label study. Participants received escalating doses of an oromucosal-administered combination containing 10 mg/mL of Δ9-THC, 25 mg/mL of CBD.

Comparison of auditory evoked potential thresholds in three shark species.

Auditory sensitivity measurements have been published for only 12 of the more than 1150 extant species of elasmobranchs (sharks, skates and rays). Thus, there is a need to further understand sound perception in more species from different ecological niches. In this study, the auditory evoked potential (AEP) technique was used to compare hearing abilities of the bottom-dwelling New Zealand carpet shark (Cephaloscyllium isabellum) and two benthopelagic houndsharks (Triakidae), the rig (Mustelus lenticulatus) and the school shark (Galeorhinus galeus).

Activation Mechanism of Nickel(0) -Heterocyclic Carbene Catalysts Stabilized by Fumarate Ligands.

Nickel(0) catalysts of -heterocyclic carbenes (NHCs) that are stabilized by electron-deficient alkenes possess desirable properties of air tolerance and ease of handling while also retaining high catalytic activities. Since catalyst stability often comes at the expense of catalytic activity, we have undertaken a detailed study of the activation mechanism of an IMes-nickel(0) catalyst stabilized by di(-tolyl) fumarate that converts the stable precatalyst form into a catalytically active species. Computational evaluation provided evidence against a simple ligand exchange as the activation mechanism for this catalyst, and a stoichiometric activation process that covalently modifies the stabilizing ligand was identified.

Fish bioacoustics: Navigating underwater sound.

Fish bioacoustics is about the sounds produced by fish, how fish hear, and what they hear. The focus of this article is on the hypothesis that some late pelagic stage reef fish larvae use the marine soundscape to locate reef settlement habitat. The hypothesis is evaluated by consideration of the nature of reef sound, hearing ability in late-stage larval fish, and direct behavioral evidence for orientation to reef sound.

Operant conditioning as a tool to assess hearing abilities in sharks.

Sharks (elasmobranchs) are an ancient, diverse group of fishes, representing a basal stage in the evolution of vertebrate hearing. Yet, our understanding of behavioural measures of hearing abilities in sharks is limited. To address this, an operant conditioning paradigm was designed, and scalloped hammerhead Sphyrna lewini and rig (spotted estuary smooth hound) Mustelus lenticulatus were successfully trained to respond to pure-tone acoustic stimuli from an underwater speaker.

Roles for cerebellum and subsumption architecture in central pattern generation.

Within vertebrates, central pattern generators drive rhythmical behaviours, such as locomotion and ventilation. Their pattern generation is also influenced by sensory input and various forms of neuromodulation. These capabilities arose early in vertebrate evolution, preceding the evolution of the cerebellum in jawed vertebrates.

Investigations into mechanism and origin of regioselectivity in the metallaphotoredox-catalyzed α-arylation of -alkylbenzamides.

A mechanistic study on the α-arylation of -alkylbenzamides catalyzed by a dual nickel/photoredox system using aryl bromides is reported herein. This study elucidates the origins of site-selectivity of the transformation, which is controlled by the generation of a hydrogen atom transfer (HAT) agent by a photocatalyst and bromide ions in solution. Tetrabutylammonium bromide was identified as a crucial additive and source of a potent HAT agent, which led to increases in yields and a lowering of the stoichiometries of the aryl bromide coupling partner.

Machine learning based assessment of small-bodied fish tracking to evaluate spoiler baffle fish passage design.

Fish passage research is important to mitigate the adverse effects of fragmented river habitats caused by waterway structures. The scale at which this research is undertaken varies from small-scale laboratory prototype studies to in-situ observations at various fish passage structures and bottlenecks. Using DeepLabCut, we introduce and evaluate a machine learning based workflow to track small-bodied fish in order to facilitate improved fish passage management.

Nickel-Catalyzed Defluorinative Coupling of Aliphatic Aldehydes with Trifluoromethyl Alkenes.

A simple procedure is reported for the nickel-catalyzed defluorinative alkylation of unactivated aliphatic aldehydes. The process involves the catalytic reductive union of trifluoromethyl alkenes with aldehydes using a nickel complex of a 6,6'-disubstituted bipyridine ligand with zinc metal as the terminal reductant. The protocol is distinguished by its broad substrate scope, mild conditions, and simple catalytic setup.

Diving into the vertical dimension of elasmobranch movement ecology.

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species.

Application of power analysis to determine the optimal reporting time frame for use in statewide trauma system quality reporting.

Background: Meaningful reporting of quality metrics relies on detecting a statistical difference when a true difference in performance exists. Larger cohorts and longer time frames can produce higher rates of statistical differences. However, older data are less relevant when attempting to enact change in the clinical setting.

Glycosyl Exchange of Unactivated Glycosidic Bonds: Suppressing or Embracing Side Reactivity in Catalytic Glycosylations.

While developing boron-catalyzed glycosylations using glycosyl fluoride donors and trialkylsilyl ether acceptors, competing pathways involving productive glycosylation or glycosyl exchange were observed. Experimental and computational mechanistic studies suggest a novel mode of reactivity where a dioxolenium ion is a key intermediate that promotes both pathways through addition to either a silyl ether or to the acetal of an existing glycosidic linkage. Modifications in catalyst structure enable either pathway to be favored, and with this understanding, improved multicomponent iterative couplings and glycosyl exchange processes were demonstrated.

Engineering P450 TamI as an Iterative Biocatalyst for Selective Late-Stage C-H Functionalization and Epoxidation of Tirandamycin Antibiotics.

Iterative P450 enzymes are powerful biocatalysts for selective late-stage C-H oxidation of complex natural product scaffolds. These enzymes represent useful tools for selectivity and cascade reactions, facilitating direct access to core structure diversification. Recently, we reported the structure of the multifunctional bacterial P450 TamI and elucidated the molecular basis of its substrate binding and strict reaction sequence at distinct carbon atoms of the substrate.

Nickel-Catalyzed Decarboxylative Coupling of Redox-Active Esters with Aliphatic Aldehydes.

The addition of alkyl fragments to aliphatic aldehydes is a highly desirable transformation for fragment couplings, yet existing methods come with operational challenges related to the basicity and instability of the nucleophilic reagents commonly employed. We report herein that nickel catalysis using a readily available bioxazoline (BiOx) ligand can catalyze the reductive coupling of redox-active esters with aliphatic aldehydes using zinc metal as the reducing agent to deliver silyl-protected secondary alcohols. This protocol is operationally simple, proceeds under mild conditions, and tolerates a variety of functional groups.

Population-based Trends in Obesity and Kidney Transplantation Among Patients With End-stage Kidney Disease.

Unlabelled: Obesity is a barrier to transplant, reducing access and leading to worse outcomes versus nonobese adults. Most transplant centers in the United States maintain body mass index (BMI) cutoffs to listing for kidney transplantation of 35 to 40 kg/m. There is little contemporary data on the prevalence of obesity among patients with end-stage kidney disease (ESKD) despite its impact on clinical outcomes and healthcare expenditures.

Nickel-catalyzed reductive coupling of unactivated alkyl bromides and aliphatic aldehydes.

A mild, convenient coupling of aliphatic aldehydes and unactivated alkyl bromides has been developed. The catalytic system features the use of a common Ni(ii) precatalyst and a readily available bioxazoline ligand and affords silyl-protected secondary alcohols. The reaction is operationally simple, utilizing Mn as a stoichiometric reductant, and tolerates a wide range of functional groups.

Reliability of hospital-level mortality in abdominal aortic aneurysm repair.

Objective: The relationship between volume and surgical outcomes has been shown for a variety of surgical procedures. The effects in abdominal aortic aneurysm repair have continued to be debated. Reliability adjustment has been used as a method to remove statistical noise from hospital-level outcomes.

Graft Survival and Segment Discards Among Split-Liver and Reduced-Size Transplantations in the United States From 2008 to 2018.

Split-liver transplantation has allocation advantages over reduced-size transplantation because of its ability to benefit 2 recipients. However, prioritization of split-liver transplantation relies on the following 3 major assumptions that have never been tested in the United States: similar long-term transplant recipient outcomes, lower incidence of segment discard among split-liver procurements, and discard of segments among reduced-size procurements that would be otherwise "transplantable." We used United Network for Organ Sharing Standard Transplant Analysis and Research data to identify all split-liver (n = 1831) and reduced-size (n = 578) transplantation episodes in the United States between 2008 and 2018.

Venous thromboembolism: risk factors in the sleeve gastrectomy era.

Background: Of complications after bariatric surgery, venous thromboembolism (VTE) has the greatest impact on mortality.

Objectives: To examine risk factors for postoperative VTE and identify high-risk patients who may benefit from prolonged prophylaxis.

Setting: National Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database METHODS: Patients who underwent primary, laparoscopic bariatric surgery 2015-2019 were identified.

Targeting zero preventable trauma readmissions.

Background: Nearly 1-in-10 trauma patients in the United States are readmitted within 30 days of discharge, with a median hospital cost of more than $8,000 per readmission. There are national efforts to reduce readmissions in trauma care, but we do not yet understand which are potentially preventable. Our study aims to quantify the potentially preventable readmissions (PPRs) in trauma care to serve as the anchor point for ongoing efforts to curb hospital readmissions and ultimately, bring preventable readmissions to zero.

Effect of injury location and severity on opioid use after trauma.

Objective: Recent data have suggested that persistent opioid use is prevalent following trauma. The effect of type of injury and total injury burden is not known. We sought to characterize the relationship between injury location and severity and risk of persistent opioid use.