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The edge-to-edge mitral valve repair technique, invented by Alfieri and colleagues, introduced valve repair as a treatment option for patients with complex diseases where standard annuloplasty and related repair techniques are insufficient, due to annular calcification and patient frailty. We retrospectively evaluated the results of a transaortic edge-to-edge mitral valve repair (Alfieri stitch) in high-risk patients who were undergoing aortic valve replacement. From February, 2012 to December, 2017, 43 patients underwent transaortic edge-to-edge mitral valve repair with concomitant aortic valve replacement at a single institution. Preoperative and postoperative echocardiograms were compared. Home telephone follow up was conducted and postoperative morbidity was examined, including the need for reoperation, stroke and cardiac arrhythmia. 30-day and long-term survival rates were also determined. Mitral regurgitation (MR) was graded semi-quantitatively as 0 (trace and/or none), mild (1), moderate (2) or moderate to severe (3-4). The patients were 74 ± 7.8 years old. 65% of the patients were male. Mean cardiopulmonary bypass time was 115 ± 37 minutes and mean cross-clamp time was 71 ± 23 minutes. There was a significant improvement in preoperative vs postoperative median MR grade (2 (IQR 2-3) vs 0 (IQR 0-1); P = 0.05). Follow-up transthoracic echocardiograms in 29 patients obtained at a median of 9 months' (range 3 - 19 months') and in 16 patients at a median of 34 months' postoperatively (range 21 - 53 months') showed mild (1 (IQR 1-2)) grade of mitral regurgitation. 30-day survival was 98%. Long term survival at 12 and 24 months' were 88% and 81% respectively. Mitral valve reoperation was conducted in 1 patient (2%), who was suffering of endocarditis. Stroke occurred in 2 patients (7%). Cardiac arrhythmia was observed in 15 patients (35%). 8 patients (19%) suffered from atrial fibrillation and 7 patients (16%) displayed atrioventricular blockage. 10 patients (23%) could be treated conservatively and 5 patients (12%) needed implantation of a pacemaker. Transaortic edge-to-edge mitral valve repair can be safely performed during aortic valve replacement in high-risk patients and improves even long-term MR grade. Postoperative cardiac arrhythmia occurs frequently. 66% of them could be treated successfully by conservative procedures.

The adsorption of DNA at mineral-water interfaces is well-established to increase its persistence in soils and sediments; however, adsorbed RNA in similar environments degrades rapidly, in some cases outpacing solution-phase degradation occurring over hours to days. Herein, we elucidate a novel abiotic mechanism by which RNA, but not DNA, degrades upon adsorption to surfaces of iron (oxyhydr)oxides such as goethite (α-FeOOH) that are abundant in soils and sediments. Upon adsorption to goethite, both single-stranded and double-stranded RNA hydrolyzed on the timescale of hours under environmentally relevant physicochemical conditions. The reaction products were consistent with iron present in goethite acting as a Lewis acid to accelerate non-selective hydrolysis of phosphodiester bonds comprising the RNA backbone. In contrast to well-established acid- or base-catalyzed RNA hydrolysis in solution, mineral-catalyzed hydrolysis was fastest at circumneutral pH, which allowed for both sufficient RNA adsorption and hydroxide concentration. We further confirmed that contact of the RNA with the mineral surface is necessary for hydrolysis to occur by demonstrating RNA degradation was inhibited by compact RNA conformation at elevated ionic strength and competitive adsorption with orthophosphate and organic matter. In addition to goethite, we observed RNA hydrolysis was also catalyzed by hematite (α-Fe2O3), but not by aluminum-containing minerals (e.g., montmorillonite). Given the extensive adsorption of nucleic acids to environmental surfaces, we anticipate previously overlooked mineral-catalyzed hydrolysis of RNA may be prevalent particularly in iron-rich soils and sediments, which must be considered across biogeochemical applications of nucleic acid analysis in environmental systems.

Amines are frequently included in formulations of the herbicides glyphosate, 2,4-D, and dicamba to increase herbicide solubility and reduce herbicide volatilization by producing herbicide-amine salts. Amines, which typically have higher vapor pressures than the corresponding herbicides, could potentially volatilize from these salts and enter the atmosphere, where they may impact atmospheric chemistry, human health, and climate. Amine volatilization from herbicide-amine salts may additionally contribute to volatilization of dicamba and 2,4-D. In this study, we established that amines applied in herbicide-amine salt formulations undergo extensive volatilization. Both dimethylamine and isopropylamine volatilized when aqueous salt solutions were dried to a residue at ∼20 °C, while lower-vapor pressure amines like diglycolamine and

The stability of RNA in aqueous systems is critical for multiple environmental applications including evaluating the environmental fate of RNA interference pesticides and interpreting viral genetic marker abundance for wastewater-based epidemiology. In addition to biological processes, abiotic reactions may also contribute to RNA loss. In particular, some metals are known to dramatically accelerate rates of RNA hydrolysis under certain conditions (i.e., 37 °C or higher temperatures, 0.15-100 mM metal concentrations). In this study, we investigated the extent to which metals catalyze RNA hydrolysis under environmentally relevant conditions. At ambient temperature, neutral pH, and ∼10 μM metal concentrations, we determined that metals that are stronger Lewis acids (i.e., lead, copper) catalyzed single-stranded (ss)RNA, whereas metals that are weaker Lewis acids (i.e., zinc, nickel) did not. In contrast, double-stranded (ds)RNA resisted hydrolysis by all metals. While lead and copper catalyzed ssRNA hydrolysis at ambient temperature and neutral pH values, other factors such as lowering the solution pH and including inorganic and organic ligands reduced the rates of these reactions. Considering these factors along with sub-micromolar metal concentrations typical of environmental systems, we determined that both ssRNA and dsRNA are unlikely to undergo significant metal-catalyzed hydrolysis in most environmental aqueous systems.