Chemoselective Hydrogenolysis of Urethanes to Formamides and Alcohols in the Presence of More Electrophilic Carbonyl Compounds.

The development of methods for the chemical recycling of polyurethanes is recognized as an urgent issue. Herein, we report the Ir-catalyzed hydrogenolysis of the urethane C-O bond to produce formamides and alcohols, where both formamides and ester and amide functionalities are tolerated. The chemoselectivity observed is counterintuitive to the generally accepted electrophilicity order of carbonyl compounds. Hydrogenolysis of urea and isocyanurate, potential byproducts in the polycondensation process of polyurethanes, is also achieved alongside the selective degradation of polyurethanes themselves, which affords diformamides and diols. The time-course of the hydrogenative polyurethane degradation reveals that the bond cleavage occurs not from the terminal, but from any part of the polymer chain. The present catalysis offers a novel method for the recycling of polyurethane-containing polymer waste.

Effects of pitavastatin on walking capacity and CD34+/133+ cell number in patients with peripheral artery disease.

This multi-center prospective non-randomized comparative study investigated the effects of pitavastatin in patients with peripheral artery disease (PAD) in terms of exercise tolerance capacities and peripheral CD34+/133+ cell numbers. At baseline, a peripheral blood test was administered to 75 patients with PAD, along with a treadmill exercise test using the Skinner-Gardner protocol to measure asymptomatic walking distance (AWD) and maximum walking distance (MWD). Each patient was assigned to a 6-month pitavastatin treatment group (n = 53) or a control group (n = 22), according to the patient's preference. The tests were repeated in both groups at 3 and 6 months. Baseline AWD and MWD correlated positively with the ankle-brachial pressure index (r = 0.342, p = 0.0032 and r = 0.324, p = 0.0054, respectively). Both AWD and MWD values improved at 3 and 6 months compared with baseline, and the degrees of their improvement were higher in the pitavastatin treatment group. CD34+/133+ cell numbers did not change over time or between groups. Eighty-seven percent of patients in the treatment group attained low-density lipoprotein cholesterol levels below 100 mg/dL after 3 months. The study shows that pitavastatin may be effective in increasing exercise tolerance capacity in patients with PAD.

Chemoselectivity change in catalytic hydrogenolysis enabling urea-reduction to formamide/amine over more reactive carbonyl compounds.

The selective transformation of a less reactive carbonyl moiety in the presence of more reactive ones can realize straightforward and environmentally benign chemical processes. However, such a transformation is highly challenging because the reactivity of carbonyl compounds, one of the most important functionalities in organic chemistry, depends on the substituents on the carbon atom. Herein, we report an Ir catalyst for the selective hydrogenolysis of urea derivatives, which are the least reactive carbonyl compounds, affording formamides and amines. Although formamide, as well as ester, amide, and carbamate substituents, are considered to be more reactive than urea, the proposed Ir catalyst tolerated these carbonyl groups and reacted with urea in a highly chemoselective manner. The proposed chemo- and regioselective hydrogenolysis allows the development of a strategy for the chemical recycling of polyurea resins.

Over-expression of Kv1.5 in rat cardiomyocytes extremely shortens the duration of the action potential and causes rapid excitation.

BACKGROUND: Genetically abnormal action potential duration (APD) can be a cause of arrhythmias that include long and short QT interval syndrome. PURPOSE: The aim of this study was to evaluate the arrhythmogenic effect of short QT syndrome induced by the over-expression of Kv1.5 in rat. METHODS: From Sprague-Dawley rats on fetal days 18-19, cardiomyocytes were excised and cultured with and without transfection with the Kv-1.5 gene using an adenovirus vector. The expression of Kv1.5 was proven by immunohistochemistry and Western blot analysis. In the culture dish and in the whole cells, the electrical activities were recorded using the whole-cell patch-clamp technique and the effects of 4-AP and verapamil were tested. RESULTS: After transfection with Kv1.5 for 12h, immunohistochemical staining and Western blot analysis were positive for Kv1.5 while they were negative in the control transfected with only Lac-Z. In the culture dish, the myocytes showed spontaneous beating at 115beats/min (bpm) just prior to the transfection with Kv1.5 and increased to 367bpm at 24h. The control myocytes showed stable beating rates during culturing. 4-AP at 200microM slowed down the rate and verapamil abolished the beating. In the whole cells, the maximal resting membrane potential was slightly depolarized and APD was extremely abbreviated both at 50% and 90% of repolarization compared with those of the control. Rapid spontaneous activities were found in a single myocyte with Kv1.5 transfection and 4-AP slowed down the frequency of the activities with a reversal of the shortened APD. CONCLUSION: The over-expression of Kv1.5 induced short APD and triggered activities in rat cardiomyocytes. This model can be used to study the arrhythmogenic substrate of short QT syndrome.