An IS26-composite transposon appears to be the main vehicle for dissemination of fosA3 in E. coli and K. pneumoniae of diverse clones.
A rhodium-catalyzed coupling reaction of 2-trimethylsilylphenylboronic acid with internal alkynes is developed for the synthesis of 2,3-disubstituted benzosilole derivatives. A range of functional groups, encompassing ketones, esters, amines, aryl bromides, and heteroarenes, are compatible, which provides rapid access to diverse benzosiloles. Sequential 2-fold coupling enables modular synthesis of asymmetrically substituted 1,5-dihydro-1,5-disila-s-indacene, a π-extended molecule of interest in organic electronics. In terms of the mechanism, the reaction involves cleavage of a C(alkyl)-Si bond in a trialkylsilyl group, which normally requires extremely harsh conditions for activation. Mechanistic studies, including effects of substituents, reveal that C-Si bond cleavage does not proceed through a hypercoordinated silicon species, but rather through a rhodium-mediated activation process. The potential use of the reaction in catalytic asymmetric synthesis of Si-chiral benzosiloles is also demonstrated.
Auscultation has been essential part of the physical examination; this is non-invasive, real-time, and very informative. Detection of abnormal respiratory sounds with a stethoscope is important in diagnosing respiratory diseases and providing first aid. However, accurate interpretation of respiratory sounds requires clinician’s considerable expertise, so trainees such as interns and residents sometimes misidentify respiratory sounds. To overcome such limitations, we tried to develop an automated classification of breath sounds. We utilized deep learning convolutional neural network (CNN) to categorize 1918 respiratory sounds (normal, crackles, wheezes, rhonchi) recorded in the clinical setting. We developed the predictive model for respiratory sound classification combining pretrained image feature extractor of series, respiratory sound, and CNN classifier. It detected abnormal sounds with an accuracy of 86.5% and the area under the ROC curve (AUC) of 0.93. It further classified abnormal lung sounds into crackles, wheezes, or rhonchi with an overall accuracy of 85.7% and a mean AUC of 0.92. On the other hand, as a result of respiratory sound classification by different groups showed varying degree in terms of accuracy; the overall accuracies were 60.3% for medical students, 53.4% for interns, 68.8% for residents, and 80.1% for fellows. Our deep learning-based classification would be able to complement the inaccuracies of clinicians' auscultation, and it may aid in the rapid diagnosis and appropriate treatment of respiratory diseases.
Abstractα′-Hydroxyenones undergo clean, catalytic amidations with amines promoted by the combination of an N-heterocyclic carbene and 1,2,4-triazole.The ubiquity of amide-containing organic compounds coupled with the generally expensive and wasteful methods for their formation have engendered intense, recent efforts in the identification and development of catalytic methods for amide-bond formation. 1 The most attractive approach, the direct catalytic coupling of carboxylic acids and amines, 2 can be achieved with certain boronic acids as catalysts under conditions involving high temperatures2a,b or the use of molecular sieves. 2c Elegant work with transition metal catalysts has made possible the formation of amides from amines and alcohols, with the formation of H 2 as the only stoichiometric byproduct. 3 Chemoselective, reagentless amide-formations, are an exciting area for the synthesis of peptides and biomolecules, 4 but the need for specialized starting materials limits the utility of these processes for the synthesis of simple amides. 5 In seeking to develop simple, waste-free methods for the synthesis of carboxylic acid derivatives, we have advanced the concept of redox esterifications and amidations. 6 These reactions, promoted by N-heterocyclic carbenes, 7 proceed via transient activated carboxylates catalytically generated by internal redox reactions of α-functionalized aldehydes including epoxyaldehydes, 8 α-haloaldehydes, 9 formyl cyclopropanes, 10 and α,β-unsaturated aldehydes. 11 Such esterifications proceed smoothly in high yield without stoichiometric amounts of reagents or byproducts. The amidations, however, are often complicated by competing imine formation and proceed only in the presence of a suitable additive such as imidazole or HOAt. 12 Thus, while feasible, this redox amidation requires further refinement to improve the yields, catalyst loadings, and scope to impact the need for simple amidation reactions. In this communication, we report such an advance in the form of catalytic amidations of α′-hydroxyenones in the presence of a triazolium precatalyst and 1,2,4-triazole as a co-catalyst.The use of α′-hydroxyenones as substrates for NHC-catalyzed reactions stems from our recent studies on their use as surrogates for α,β-unsaturated aldehydes. 13 These starting materials are attractive due to their facile, one-step preparation from widely available starting materials, 14 their stability towards long-term storage, and their tendancy to be crystalline products. In contrast, the corresponding α,β-unsaturated aldehydes often require multi-step syntheses employing expensive and wasteful reagents. 15 We also recognized that the use of α′- NIH Public Access Author ManuscriptChem Commun (Camb) We were pleased to see that esterifications from alcohols and the α′-hydroxyenones proceeded smoothly, but initial attempts to extend this to amidations gave rise to only small amounts of the desired products. Reasoning that the use of a suitable co-catalyst was essential for the success of the amidation...
Late-onset hyponatremia (LOH), hyponatremia occurring after two weeks of age with the achievement of full feeding, is the result of a negative sodium balance caused by inadequate salt intake or excessive salt loss due to immature renal or intestinal function in preterm infants. The aims of our study were to identify the risk factors for LOH and its influence on neonatal outcomes. This was a retrospective cohort analysis of 161 preterm infants born before 34 weeks of gestation between June 2009 and December 2010 at Seoul National University Hospital. LOH was defined as a sodium level ≤ 132 mEq/L or 133-135 mEq/L with oral sodium supplementation. LOH occurred in 49 (30.4%) of the studied infants. A lower gestational age, a shorter duration of parenteral nutrition, the presence of respiratory distress syndrome, the use of furosemide, and feeding with breast milk were significant risk factors for LOH. In terms of neonatal outcomes, the infants with LOH had longer hospital stays and higher risks of bronchopulmonary dysplasia and retinopathy of prematurity requiring surgery. LOH lasting at least 7 days significantly increased moderate to severe bronchopulmonary dysplasia, periventricular leukomalacia, and extra-uterine growth retardation. LOH is commonly observed in preterm infants; it may be a risk factor for bronchopulmonary dysplasia and retinopathy of prematurity or a marker of illness severity.
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