Convergent Biocatalytic Mediated Synthesis of siRNA.

New technologies are required to combat the challenges faced with manufacturing commercial quantities of oligonucleotide drug substances which are required for treating large patient populations. Herein we report a convergent biocatalytic synthesis strategy for an Alnylam model siRNA. The siRNA chemical structure includes several of the unnatural modifications and conjugations typical of siRNA drug substances.

Synthesis of bicyclic ethers by a palladium-catalyzed oxidative cyclization-redox relay-π-allyl-Pd cyclization cascade reaction.

Bicyclic ether scaffolds are found in a variety of natural products and are of interest in probe and drug discovery. A palladium-catalyzed cascade reaction has been developed to provide efficient access to these scaffolds from readily available linear diene-diol substrates. A Pd redox-relay process is used strategically to transmit reactivity between an initial oxypalladative cyclization and a subsequent π-allyl-Pd cyclization at remote sites.

Respiratory Pathogens in Children 1 Month to 5 Years of Age Presenting With Undifferentiated Acute Respiratory Distress in 2 District-Level Hospitals in Ghana.

Ghanaian children (2176) aged <5 years who presented with undifferentiated acute respiratory distress were tested for respiratory pathogens using a BioFire FilmArray polymerase chain reaction assay. Rhinovirus and/or enterovirus was detected in 36% of the assays, respiratory syncytial virus in 11%, and parainfluenza in 7%. Respiratory syncytial virus and metapneumovirus were detected more frequently in the rainy season than in the dry season.

Continuous positive airway pressure for children with undifferentiated respiratory distress in Ghana: an open-label, cluster, crossover trial.

Background: In low-income and middle-income countries, invasive mechanical ventilation is often not available for children at risk of death from respiratory failure. We aimed to determine if continuous positive airway pressure (CPAP), a form of non-invasive ventilation, decreases all-cause mortality in children with undifferentiated respiratory distress in Ghana.

Methods: This open-label, cluster, crossover trial was done in two Ghanaian non-tertiary hospitals where invasive mechanical ventilation is not routinely available.

Diastereoselective Synthesis of Highly Substituted Tetrahydrofurans by Pd-Catalyzed Tandem Oxidative Cyclization-Redox Relay Reactions Controlled by Intramolecular Hydrogen Bonding.

Palladium-catalyzed oxidative cyclization of alkenols provides a convenient entry into cyclic ethers but typically proceeds with little or no diastereoselectivity for cyclization of trisubstituted olefins to form tetrahydrofurans due to the similar energies of competing 5-membered transition-state conformations. Herein, a new variant of this reaction has been developed in which a PdCl/1,4-benzoquinone catalyst system coupled with introduction of a hydrogen-bond acceptor in the substrate enhances both diastereoselectivity and reactivity. Cyclization occurs with 5-exo Markovnikov regioselectivity.

Development of a voltammetric assay, using screen-printed electrodes, for clonazepam and its application to beverage and serum samples.

This paper describes the development of an electrochemical assay based on screen-printed carbon sensors for the determination of clonazepam in serum and in wine. The cyclic voltammetric behaviour of the drug was investigated and the effects of pH and scan rate on the peak current and peak potential determined. Two reduction peaks were recorded on the initial negative going scan, which were considered to result from the 2e(-), 2 H(+) reduction of the 4,5-azomethine and from the 4e(-), 4 H(+) reduction of the 7-NO2 to a hydroxylamine.

No acid required: 4π and 6π electrocyclization reactions of dienyl diketones for the synthesis of cyclopentenones and 2H-Pyrans.

The 1,6-conjugate addition of nucleophiles to dienyl diketones produces either cyclopentenone or 2H-pyran products with high selectivity through either Nazarov (4π) or 6π electrocyclization, respectively. The outcome of the reaction is dependent upon the nature of the nucleophile used. Nucleophiles that are anionic or easily deprotonated exclusively produce cyclopentenones via Nazarov cyclization, whereas the neutral nucleophile DABCO promotes 6π cyclization to afford 2H-pyrans.

Aftermath of a clinical trial: evaluating the sustainability of a medical device intervention in Ghana.

A randomized controlled trial recently demonstrated that continuous positive airway pressure (CPAP) effectively decreases respiratory rate in children presenting to Ghanaian district hospitals with respiratory distress. A follow-up study 16 months later evaluated the extent to which the skills and equipment necessary for CPAP use have been maintained. Seven of eight CPAP machines were functional, but five of eight oxygen concentrators and three of four electric generators were non-functional.

Cyclization cascades initiated by 1,6-conjugate addition.

Dienyl diketones containing tethered acetates selectively undergo two different 1,6-conjugate addition-initiated cyclization cascades. One is a 1,6-conjugate addition/cyclization sequence with incorporation of the nucleophile, and the other is catalyzed by DABCO and is thought to proceed via a cyclic acetoxonium intermediate. The reaction behavior of substrates lacking the tethered acetate was also studied.

The fatty acid oxidation product 15-A3t-isoprostane is a potent inhibitor of NFκB transcription and macrophage transformation.

Fatty acids such as eicosapentaenoic acid (EPA) have been shown to be beneficial for neurological function and human health. It is widely thought that oxidation products of EPA are responsible for biological activity, although the specific EPA peroxidation product(s) which exert these responses have not yet been identified. In this work we provide the first evidence that the synthesized representative cyclopentenone IsoP, 15-A(3t)-IsoP, serves as a potent inhibitor of lipopolysaccharide-stimulated macrophage activation.

Conjugate addition-initiated Nazarov cyclization.

A reaction sequence involving the 1,6-conjugate addition of a nucleophile to a dienyl diketone followed by Nazarov cyclization is described. Several nucleophiles are identified as competent initiators for the sequence. A different reaction outcome is observed when catalytic amounts of nucleophile are employed, involving elimination of the nucleophile after the electrocyclization.

p66(shc)'s role as an essential mitophagic molecule in controlling neuronal redox and energetic tone.

Stroke is the leading cause of adult disability in the U.S. and is now recognized as a global epidemic.

Essential role of the redox-sensitive kinase p66shc in determining energetic and oxidative status and cell fate in neuronal preconditioning.

Ischemic preconditioning is a phenomenon in which low-level stressful stimuli upregulate endogenous defensive programs, resulting in subsequent resistance to otherwise lethal injuries. We previously observed that signal transduction systems typically associated with neurodegeneration such as caspase activation are requisite events for the expression of tolerance and induction of HSP70. In this work, we sought to determine the extent and duration of oxidative and energetic dysfunction as well as the role of effector kinases on metabolic function in preconditioned cells.

Electrophilic cyclopentenone neuroprostanes are anti-inflammatory mediators formed from the peroxidation of the omega-3 polyunsaturated fatty acid docosahexaenoic acid.

The omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) possesses potent anti-inflammatory properties and has shown therapeutic benefit in numerous inflammatory diseases. However, the molecular mechanisms of these anti-inflammatory properties are poorly understood. DHA is highly susceptible to peroxidation, which yields an array of potentially bioactive lipid species.

Formation of highly reactive cyclopentenone isoprostane compounds (A3/J3-isoprostanes) in vivo from eicosapentaenoic acid.

Omega-3 (omega-3) polyunsaturated fatty acids (PUFAs) found in marine fish oils are known to suppress inflammation associated with a wide variety of diseases. Eicosapentaenoic acid (EPA) is one of the most abundant omega-3 fatty acids in fish oil, but the mechanism(s) by which EPA exerts its beneficial effects is unknown. Recent studies, however, have demonstrated that oxidized EPA, rather than native EPA, possesses anti-atherosclerotic, anti-inflammatory, and anti-proliferative effects.

Quantification of F2-isoprostanes in biological fluids and tissues as a measure of oxidant stress.

Oxidant stress has been implicated in a wide variety of disease processes. One method to quantify oxidative injury is to measure lipid peroxidation. Quantification of a group of prostaglandin F(2)-like compounds derived from the nonezymatic oxidation of arachidonic acid, termed the F(2)-isoprostanes (F(2)-IsoPs), provides an accurate assessment of oxidative stress both in vitro and in vivo.

In vivo oxidative damage in rats is associated with barbiturate response but not other cytochrome P450 inducers.

Previously published studies have shown that cytochrome P450 (P450) enzyme systems can produce reactive oxygen species and suggest roles of P450s in oxidative stress. However, most of the studies have been done in vitro, and the potential link between P450 induction and in vivo oxidative damage has not been rigorously explored with validated biomarkers. Male Sprague-Dawley rats were pretreated with typical P450 inducers (beta-naphthoflavone, phenobarbital (PB), Aroclor 1254, isoniazid, pregnenolone 16alpha-carbonitrile, and clofibrate) or the general P450 inhibitor 1-aminobenztriazole; induction of P4501A, -2B, -2E, -3A, and -4A subfamily enzymes was confirmed by immunoblotting and the suppression of P450 by 1-aminobenztriazole using spectral analysis.

Identification of novel autoxidation products of the omega-3 fatty acid eicosapentaenoic acid in vitro and in vivo.

Increased intake of fish oil rich in the omega-3 fatty acids eicosapentaenoic acid (EPA, C20:5 omega-3) and docosahexaenoic acid (DHA, C22:6 omega-3) reduces the incidence of human disorders such as atherosclerotic cardiovascular disease. However, mechanisms that contribute to the beneficial effects of fish oil consumption are poorly understood. Mounting evidence suggests that oxidation products of EPA and DHA may be responsible, at least in part, for these benefits.

Functional selectivity of G protein signaling by agonist peptides and thrombin for the protease-activated receptor-1.

Thrombin activates protease-activated receptor-1 (PAR-1) by cleavage of the amino terminus to unmask a tethered ligand. Although peptide analogs can activate PAR-1, we show that the functional responses mediated via PAR-1 differ between the agonists. Thrombin caused endothelial monolayer permeability and mobilized intracellular calcium with EC(50) values of 0.

Thrombin modulates the expression of a set of genes including thrombospondin-1 in human microvascular endothelial cells.

Thrombospondin-1 (THBS1) is a large extracellular matrix glycoprotein that affects vasculature systems such as platelet activation, angiogenesis, and wound healing. Increases in THBS1 expression have been liked to disease states including tumor progression, atherosclerosis, and arthritis. The present study focuses on the effects of thrombin activation of the G-protein-coupled, protease-activated receptor-1 (PAR-1) on THBS1 gene expression in the microvascular endothelium.