Esterification of Cyclic N6-threonylcarbamoyladenosine during RNA Sample Preparation

The continuous deciphering of crucial biological roles of RNA modifications and their involvement in various pathological conditions, together with their key roles in the use of RNA-based therapeutics, has reignited interest in studying the occurrence and identity of non-canonical ribonucleoside structures during the past years. Discovery and structural elucidation of new modified structures is usually achieved by combination of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) at the nucleoside level and stable isotope labeling experiments. This approach, however, has its pitfalls as demonstrated in the course of the present study: we structurally elucidated a new nucleoside structure that showed significant similarities to the family of (c)t6A modifications and was initially considered a genuine modification, but turned out to be an in vitro formed glycerol ester of t6A. This artifact is generated from ct6A during RNA hydrolysis upon addition of enzymes stored in glycerol containing buffers in a mildly alkaline milieu, and was moreover shown to undergo an intramolecular transesterification reaction. This warrants extra caution  in the discovery of new RNA modifications and in quantification of known modified structures, in particular chemically labile modifications that might suffer from exposure to putatively harmless reagents during the diverse steps of sample preparation.

Complementary mechanochemical and biphasic approaches for the synthesis of organic thiocyanates using hexacyanoferrates as non-toxic cyanide sources

Herein, we describe two complementary approaches towards various organic thiocyanates that are affordable, reliable and follow the principles of sustainable chemistry, starting from commercially available thiols or disulfides. Additionally, the application of this mild method to the first total synthesis of psammaplin B is demonstrated. Non-toxic and inexpensive ferricyanide is used as the cyanide source, which can be activated either in a mechanochemical, solvent-free approach, or in a biphasic solvent system allowing easier work-up. A total of 27 examples is demonstrated, with up to quantitative yields.

Cell Adhesion on UV-Crosslinked Polyurethane Gels with Adjustable Mechanical Strength and Thermoresponsiveness

Temperature-responsive polyurethane (PU) hydrogels represent a versatile material platform for modern tissue engineering and biomedical applications. However, besides intrinsic advantages such as high mechanical strength and a hydrolysable backbone composition, plain PU materials are generally lacking bio-adhesive properties. To overcome this shortcoming, the authors focus on the synthesis of thermoresponsive PU hydrogels with variable mechanical and cell adhesive properties obtained from linear precursor PUs based on poly(ethylene glycol)s (pEG) with different molar masses, isophorone diisocyanate, and a dimerizable dimethylmaleimide (DMMI)-diol. The cloud point temperatures of the dilute, aqueous PU solutions depend linearly on the amphiphilic balance. Rheological gelation experiments under UV-irradiation reveal the dependence of the gelation time on photosensitizer concentration and light intensity, while the finally obtained gel strength is determined by the polymer concentration and spacing of the crosslinks. The swelling ratios of these soft hydrogels show significant changes between 5 and 40 °C whereby the extent of this switch increases with the hydrophobicity of the precursor. Moreover, it is shown that the incorporation of a low amount of catechol groups into the networks through the DMMI dimerization reaction leads to strongly improved cell adhesive properties without significantly weakening the gels.

Association between reported use of inhaled triamcinolone and differential short-term responses to aerosolized albuterol in asthmatics in an emergency department setting

Forty-four adult patients with acute asthma were treated with albuterol at a rate of 15 mg/h over 2 h. Analysis of covariance showed a significantly higher baseline adjusted mean for both percent predicted forced expiratory volume in 1 s (PFEV1) (p = 0.045) and percent predicted forced vital capacity (PFVC) (p = 0.022) at 50 and 110 min for the patients who reported triamcinolone use. Although heart rates decreased overall during the first hour of albuterol treatment, a rise in mean heart rate occurred during the second hour of treatment only in patients reporting triamcinolone use (p = 0.005). After accounting for the effects of parenteral corticosteroids, the effect of reported triamcinolone use remained significant. These data suggest that use of inhaled corticosteroids in this context may be associated with enhanced local and systemic beta-responsiveness, and if a causal relationship could be confirmed, this may constitute yet another advantage of early inhaled corticosteroid treatment in asthma. These data also suggest that chronotropic effects of high-dose albuterol should be monitored in patients using inhaled triamcinolone.

Continuous versus intermittent albuterol nebulization in the treatment of acute asthma

STUDY OBJECTIVES

To compare bronchodilation, chronotropic effects, and side effects of the same dose of nebulized albuterol when given by either intermittent or continuous administration.

DESIGN

A randomized assignment of patients to one of the two methods of albuterol nebulization.

SETTING

Adult emergency department in an urban public hospital.

TYPE OF PARTICIPANTS

Adult patients with acute exacerbations of asthma.

INTERVENTIONS

Administration of 30 mg albuterol given over 110 minutes by either continuous or intermittent aerosolization.

MEASUREMENTS

FEV1, forced vital capacity, heart rate, and systolic and diastolic blood pressures were measured immediately before treatment and then hourly for two hours. Side effects, symptoms, subsequent admission, and discharge also were noted.

MAIN RESULTS

An overall significant decrease in heart rate was observed, indicating the lack of significant chronotropic effects with this dose of albuterol. Both treatments resulted in significant spirometric improvement without a significant treatment difference for the entire group. A difference, however, was found in the relative rates of FEV1 improvement with the two treatments depending on whether patients had an initial FEV1 less than or more than 50% predicted (P = .05). A secondary analysis on patients with an initial FEV1 less than percent predicted demonstrated a higher rate of percent predicted FEV1 increase with the continuously nebulized albuterol group (P = .03).

CONCLUSION

This study demonstrates that albuterol can be given safely at this dose by either intermittent or continuous nebulization. Future studies should examine whether continuous nebulization has a reproducible advantage over intermittent nebulization in patients with more severe obstruction.